Systems and methods of UTF-8 pattern matching

ABSTRACT

Systems and methods are described for efficiently processing, searching and/or rewriting variable width encoded data, such as UTF-8 encoded data, will be described. Embodiments of the systems and methods modify and adapt search algorithms, such as the Horspool and Wu-Manber algorithms, to efficiently process and manage searching of variable width encoded text in large blocks of text, such as text that may be carried via a stream of packets thru a network device, such as an intermediary device.

RELATED APPLICATION

The present application claims the benefit of and priority to U.S.Provisional Application No. 61/468,470, entitled “Systems and MethodsFor Rewriting A Data Stream Containing UTF-8 Encoding Via AnIntermediary” and filed on Mar. 28, 2011, which is incorporated hereinby reference in its entirety for all purposes.

FIELD OF THE DISCLOSURE

The present application generally relates to modifying data. Inparticular, the present application relates to identifying and rewritingUTF-8 encoded packets as they move through an intermediary device.

BACKGROUND OF THE DISCLOSURE

There exist different systems that provide a rewrite feature, whichpermits a system to rewrite packet content. In some instances, thecontent that needs to be rewritten can be content that flows through themulti-core system. Current systems can provide rewrite support at thehyper-text-transfer protocol (HTTP) level. Further, current systems canhold an entire response before performing a rewrite.

In many instances, current systems that provide rewrite support mayrequire that an entire response be accumulated before performing therewrite. In these instances, the requirement to hold the response canlead to increased memory consumption and increased response timelatency. Other systems may require unnecessary overhead actions such asthe requirement to copy a response to a buffer. Still other system mayrewrite only an amount of data that could be accumulated. In othersystems, multiple times body parsing can be performed such that thenumber of times a body is parsed can equal the number of actionsrewriting a particular pattern with a new pattern. In many of thesesystems, the additional requirements can use up resources and memorythereby reducing the throughput or the amount of packets rewrittenduring a particular period of time.

BRIEF SUMMARY OF THE DISCLOSURE

In light of the drawbacks of current systems, there exists a need for asystem that can rewrite a stream of packets, hold a minimum number ofpackets and use a minimum amount of resources. In particular, thesystems and methods of the present disclosure provide more efficientsearching of multi-byte character encoding of data or text, such aswithin a stream of packets.

UTF-8 is a multi-byte character encoding for Unicode that is oftenutilized by standards conforming to the Internet Assigned NumbersAuthority (IANA) list, which includes CSS, HTML, XML and HTTP headers.The increasing use of UTF-8 can be attributed to itsbackward-compatibility with ASCII, and because it does not need toemploy byte order marks (BOM). Because of its dominant usage by theindustry, there is a need for a system capable of searching multipleUTF-8 encoded patterns in large blocks of text.

Current systems use various algorithms to identify substrings instrings, also known as multi-pattern matching. Examples of suchalgorithms include the Wu-Manber (as described in Sun Wu and Udi Manber,“A Fast Algorithm for Multi-Pattern Searching,” Technical ReportTR-94-17, University of Arizona, (1994) (available athttp://webglimpse.net/pubs/TR94-17.pdf), the contents of which areincorporated by referenced in its entirety) and Horspool algorithms.

The Wu-Manber algorithm is an improvement of the Boyer-Moore algorithm.The Wu-Manber algorithm, as known in the art, is a multi-stage algorithmthat employs three tables: the SHIFT table, HASH table, and PREFIXtable. As with the Boyer-Moore algorithm, the verification, or attemptsto check whether a match exists at a particular position, worksbackwards. The SHIFT table is used to determine how many characters inthe text can be shifted or skipped when the text is scanned. The HASHand PREFIX tables are used to determine which pattern is a candidate forthe match and to verify the match.

The Wu-Manber is used to search for multiple patterns at the same time.P={p₁, p₂, . . . , p_(k)} represents a set of patterns, which arestrings of characters from a fixed alphabet. Each p_(i) is a string.l_(min) represents the minimum length of a pattern in P and l_(max)represents the maximum length of a pattern in P. T={t₁, t₂, . . . t_(N)}is a large text consisting of characters of the same fixed alphabet asP. M is the total size of all patterns, where M=k*l_(min) and c is thesize of the fixed alphabet. The essence of Wu-Manber is to utilizeblocks of characters of length B to preprocess patterns by generatingtables. If the string of B characters in the text do not appear in anyof the patterns, then the search shifts by l_(min)−B+1. Each string ofsize B is mapped to an integer used as an index to the SHIFT table. Thevalues in the SHIFT table determine how far to shift while scanning T.Let X=x₁ . . . x_(B) is the B characters in the text that are beingscanned, and X is mapped into the i′th entry of the SHIFT table. The twocases are:

-   -   If X does not appear as a substring in any pattern in P, then        the search shifts (l_(min)−B+1) characters. In SHIFT[i], the        system stores (l_(min)−B+1).    -   If X appears as a substring of some patterns of P, the rightmost        occurrence of X in any of the patterns is identified. If X ends        at the position q of P_(j) and assuming that X does not end at        any position greater than q in any other pattern. Then l_(min)−q        is stored in SHIFT[i].

To compute the SHIFT table consider separately each pattern p_(i)=a₁ a₂. . . a_(lmin). Each substring of p_(i) of size B a_(j−b+1) . . . a_(j)is mapped into SHIFT, and the corresponding value is set to the minimumof its current value (the initial value for all of them is l_(min)−B+1)and l_(min)−j (the amount of shifting required to get to thissubstring). During the search phase, the search positions is shiftedalong the text as long as the SHIFT value is positive. When the SHIFTvalue is zero, the text to the left of the search position might be oneof the pattern strings.

The exact same integer to index into another table, called HASH. Thei′th entry of the HASH table, HASH[i], contains a pointer to a list ofpatterns whose last B characters hash into i. The HASH table holds onlythe patterns whereas the SHIFT table holds all possible strings of sizeB.

There are some challenges for implementing the Wu-Manber algorithm forpatterns encoded using UTF-8. For case-insensitive string comparison,converting both the strings into the same case before the comparison isvery inefficient. This additional step would reduce the efficiency ofthe algorithm to an almost linear efficiency, unlike the originalsub-linear efficiency of the Wu-Manber algorithm. Additionally,Wu-Manber requires jumping to an identified Nth character in the text.Since each character in ASCII is single byte, this is a constant timeoperation. However, because UTF-8 is a multi-byte encoding, thisoperation becomes linear as jumping to a character position requirestraversing the entire text in between counting the characters. This alsoreduces the algorithm to a linear efficiency from sub-linear efficiency.

Another well-known commonly utilized algorithm for multi-patternmatching of strings is the Horspool algorithm. Like the Wu-Manber, theHorspool algorithm is a modification of the Boyer-Moore algorithm. TheHorspool algorithm is a simplification of the Boyer-Moore algorithm andhas an average complexity of O(N) and a complexity of O(MN) in the worstcase, where N represents the length of the search string and Mrepresents the length of the pattern. The algorithm is described in moredetail in the paper written by Nigel Horspool entitled “Practical FastSearching in Strings” (Software-Practice and Experience, vol. 10, pp501-506 (1980)) the contents of which are incorporated by referenced inits entirety. The Horspool algorithm also performs preprocessing of thepattern, as a means of determining how far to skip ahead in the searchtext if an initial match attempt fails. The results of the preprocessingare saved in a vector that is used during the search process.

Example

Text: G C A T C G C A G A G A G T A T A C A G T A C G Pattern:G C A G A G A G

The jump values for the pattern characters are:

G C A G A G A G 7 6 5 4 3 2 1

The jump value of a character is its position from the end (withoutconsidering the last character). If a character is repeated in pattern,the minimum position is taken. For the example listed above, the jumpvalues for the pattern are:

A=1

G=2

C=6

The values listed reflect the minimum position of the character in thestring from the end while ignoring the last position.

Initial Values:

Text: G C A T C G C A G A G A G T A T A C A G T A C G Pattern:G C A G A G A G

Step 1:

Compare the last character of the pattern with corresponding characterof text. The jump is always based on this text character, which is knownas the pivot character. In the given example, since the last characterof the pattern (G) does not match the corresponding character of thetext (A), there is a mismatch, and the mismatch is at the text characterA (the pivot character for this step), jump the pattern right by A'sjump value (in the actual implementation, a pointer to the text is keptand move the pointer).

Positions after Step 1:

Text: G C A T C G C A G A G A G T A T A C A G T A C G Pattern:  G C A G A G A G

Step 2:

Though the last character of the pattern matches the correspondingcharacter in the text, the actual match failed. So the system progressesagain by the jump value of the pivot character (G)

Positions after Step 2:

Text: G C A T C G C A G A G A G T A T A C A G T A C G Pattern:      G C A G A G A G

Step 3:

Since the last character match of the pattern matches the correspondingcharacter in the text, the system starts comparing from beginning to seeif it is a perfect match. In this case, since there is a mismatch in thefirst character itself (G does not match T), the system jumps again byjump value of the pivot character (G in this case)

Positions after Step 3:

Text: G C A T C G C A G A G A G T A T A C A G T A C G Pattern:          G C A G A G A G

Step 4: The last character of the pattern is matched and the strings arecompared from the beginning. As shown in the example, a match was found.

There are some challenges for implementing the Horspool algorithm forpatterns encoded using UTF-8. Pre-processing and storing pre-processedpattern is easy in ASCII cases as the total number of ASCII character isless than those encoded in UTF-8 and the difference between the upperand corresponding lower case character is same for all of ASCII. But forUTF-8 characters, efficient data structures may be required for storingthe pre-processed string, and case insensitive comparison becomescomplicated as there is no direct method to find the other case of acharacter except by referencing the case map tables. Forcase-insensitive string comparisons, converting both the strings intosame case before the comparison is very inefficient. This reduces theefficiency of the algorithm to an almost linear efficiency, rather thanthe original sub-linear efficiency. The regular Horspool algorithmrequires jumping to some Nth character in the text. Since each characterin ASCII is single byte, this is a constant time operation. But inUTF-8, this is linear as jumping to a character position requirestraversing the entire text in between counting the characters. This alsomakes the algorithm linear from sub-linear.

In the case insensitive implementation, while calculating the prefix andsuffix tables, all the UTF-8 patterns are converted into thecorresponding lower case patterns and the hash values and correspondingjump values are calculated on them as in case of the regular Wu-Manberalgorithm.

A block of three bytes is used for the hash computation. This differsfrom Wu-Manber because the system utilizes bytes instead of characterswhile calculating the SHIFT and HASH tables. In some embodiments,another length of bytes can be used based on the patterns or statisticalanalysis. For example, if a pattern has a byte length of 10, afterconverting the pattern into its lower case, the bytes 8, 9, and 10 areused to calculate a hash. The jump value for this tuple is zero. Againstthe hash value of bytes (8, 9, 10), the jump value 0 is stored. Whenevera zero jump of zero is recorded, in the same table (or in an alternatetable), the pattern is also stored. Therefore, if the jump value at ahash index is zero, all the corresponding patterns are easilyaccessible. This is useful while searching in text. Whenever a pivotblock with zero jump is found, all the corresponding patterns are takenand checked to verify if any of them actually match the text.

The modified algorithm may require jumping in the text. To retain thesub-linear running time complexity, byte jumps are used instead ofcharacter jumps. This can cause the jumps to be in the middle of acharacter. In some cases this helps to decide that there is no match. Insome cases, when the jump is in the middle of a character, the systemgoes to the beginning of the character and proceeds with the algorithm.

Initially, the minimum byte length of all the patterns is taken and thesystem jumps by the minimum pattern in the text. From that location,using the last three bytes, the hash value is calculated. Because it isa case insensitive string search (and accordingly the hash tables arecalculated on lower case UTF-8 strings), the bytes are converted intolower case before calculating hash. Since only characters can beconverted into lower case, the minimal valid UTF-8 string that containsthe selected 3 bytes is taken. The string is converted into a lower caseUTF-8 string, and the three bytes from the same location are used forhash value calculation. Because of this step, the algorithm works onlyfor the simple case where the UTF-8 character length doesn't change withthe case conversion. Based on this hash value, the jump is identified.

In some embodiments of the present disclosure, the modified Wu-Manberalgorithm may consist of the following steps:

1. Initialization: Set a pointer to the beginning of the text. Move thepointer to the pivot block (by taking the minimum byte length lmin amongall the patterns and by moving the pointer to lmin-3 bytes, where 3 isthe block size).

2. For the three bytes in the pivot block, calculate the hash value. Forthis, find the minimal valid UTF-8 string that contains these threebytes, and convert the string into lower case. From the lower casestring, select the exact three byte positions and calculate the hashvalue, and find the jump from the hash value.

3. If the jump is 0 at this hash, then one or more of the patterns couldmatch at this location. In the pre-processing step, when a zero jump isrecorded in the hash table, a list of patterns that have zero jumps atthis hash is also maintained. Each of those patterns are taken andchecked to see if there is any match. Any such search may requirelooking back in the text by appropriate length based on the patternlength. If this point in the text is not to a character boundary, thatpattern can be skipped even before comparing any characters. If thispoint is at a character boundary, a case insensitive UTF-8 stringcomparison is performed to check if the pattern matches that part of thetext. If it matches, then a match to this string is declared. The systemcontinues to match other strings in the list of patterns until the listfor this hash is exhausted. Set the jump to 1. Note: the system can alsodo prefix matching of the patterns as the Wu-Manber paper describes.

4. Jump in the text by the jump value. If such a jump exceeds the textboundary, declare no more matches. Otherwise take last three bytes atthat pointer as the pivot block.

5. Go to step 2.

In the regular Horspool, the jump value of a character is its positionin the pattern from the end. If a character is repeated more than once,the minimum of all its positions will be its jump value. To store thejump value, an index table is needed since linear search for findingjump value of a character is inefficient (as one has to find the jumpvalue of some character in each iteration of the algorithm). For ASCII,a plain index table can be used to store the jump values as the ASCIIcharacters are small in number. In UTF-8, the number of possiblecharacters is huge. For each UTF-8 character in the pattern, itscorresponding Unicode value is calculated. If it is upper case, then thecorresponding lower case Unicode value is calculated. In either case ahash is applied on the Unicode value. Four hash tables are maintained,one for each size as UTF-8 character can be at most 4 bytes (based onthe statistical analysis, space restrictions and hash collisions, thiscan either be decreased or increased). If there is a hash collision, theskip value should be minimum of two. That is because, in the absence ofany hash collisions, the jump value of a character ensures that afterthe jump, the pivot character of the text is aligned with the samecharacter in the pattern. Without such alignment, the system could notidentify any match. In case of collision, by taking the minimum of theexisting and new values, the jump many not align the pivot in the textwith the same character in pattern, but it ensures that no matches aremissed. Taking minimum of two hash values can be easily achieved byprocessing the pattern from the back instead of from front.

In the skip tables, the jump value of a character is its position in thepattern from the back. But if the character position in the jump tableis kept, then the system would have to jump by those characters in UTF-8text, and the system will be reduced to a character by charactermatching, which is far less efficient. Thus, the position of thecharacter in the pattern is not kept. Rather, a corresponding bytelength is used. That way, while using these values to jump in the text,the system can do a direct jump instead of counting the characters.

The last character of the pattern is compared to the text. And if thereis a match, then the entire pattern is compared. To compare twocharacters case insensitively, the system needs to calculate theircorresponding lower (or upper) case Unicode values. Since the pattern isknown beforehand, in the pre-processing step, the system calculates thelowercase Unicode value of all the characters of the pattern and storesit. The byte length and the length of the last character of the patternare also stored. In streaming text, the pre-processed pattern issearched.

In dealing with un-alignments, the algorithm may require jumping in thetext. To retain the sub-linear running time complexity, byte jumps areused instead of character jumps. This can cause the jumps to be in themiddle of a character. In some cases this helps to decide that there isno match. In some cases, when in the middle of a character, the systemproceeds to the beginning of the character and proceeds with thealgorithm.

In dealing with choosing pivot element, take the last character of thepattern and the corresponding character in text to do a case-insensitivecomparison. If the pattern has 5 characters, the system needs to go tothe fifth character in the text and compare it with fifth character ofthe pattern. But going to fifth character in text is linear time. So,instead the byte length of the pattern is used. Say if the lastcharacter length in pattern is 4, and if pattern is 20 bytes long, thenthe last character starts from 17th byte. In the text also, the systemgoes to the 17th byte directly and see if it is aligned to a characterboundary. The system goes to the nearest aligned character towards thebeginning of the text. In either case the lowercase Unicode value of thecharacter is found in the text (this value is the pivot element). Incase of a mismatch, the system finds the jump value of this from jumptables and jump in the text such that the comparison point of the textis moved to the right and compare it with that of the pattern.

In some embodiments of the present disclosure, the modified Horspoolalgorithm may consist of the following steps:

1. Initialization: Set a pointer to the beginning of the text. Based onthe pattern length and last character length, jump in the text to itspivot element. In the initialization, if any such jump goes to themiddle of a character, go to the next character. But in the subsequentsteps, in case of any such misalignments, go to the beginning of thecharacter2. Compare the lower case Unicode value of the pivot element against thecorresponding value of the last character of the pattern. If thecharacters compared above are same then go to beginning of the pattern,and jump to the corresponding byte location of the text to compare thepattern against that part of the text. But this jump in text might be tothe middle of a character, which clearly signifies no match. But if thejump is to a character boundary, then do a case insensitive comparisonof the two strings.3. If there is a match, exit by declaring the match position (ifsearching for the multiple occurrences of the pattern, algorithm can becontinued until the end of the text is reached). If there is a mismatch,then jump by the jump value of the current pivot element.4. If this jump meets or crosses the end of the text, exit thealgorithm. If it is to the beginning or middle of a character, take thatcharacter as pivot element.5. Go to step 2.

In one aspect, the present disclosure is related to systems and methodsfor case insensitive searching of a variable width encoded pattern in ablock of text. A device may determine for each character in a patternfor which to search for a match within a block of text, a correspondinglower case Unicode value. The pattern may be made up of variable-widthencoded characters. The device may establish an index table of jumpvalues for the pattern, the index table comprising a hash to eachcorresponding lower case Unicode value that identifies a number of bytelengths for the corresponding character. Responsive to the index tableof jump values, the device may jump a pointer to the block of text to apivot element in the block of text based on a byte length of the patternand the byte length of a last character of the pattern. The devicecompares a lower case Unicode value of the pivot element to thecorresponding lower case Unicode value of the character of the lastcharacter of the pattern.

In some embodiments, the device determines that a character in thepattern is upper case and calculating a lower case Unicode value. Thepattern may be UTF-8 encoded or otherwise include variable-width encodedcharacters that are UTF-8 encoded. In some embodiments, the deviceestablishes index tables for each of size of variable-width encodedcharacters. In some embodiments, the device sets the pointer at abeginning of the block of text. In some embodiments, the devicedetermines that the pointer has jumped to a middle of a character in theblock of text. Responsive to the determination that the pointer hasjumped to the middle of the character in the block of text, the devicemay move or set the pointer to beginning of the character. In someembodiments, the device determines that the jump to the pivot element isa jump to a character boundary and responsive to determining that thejump is to the character boundary, the device performs the comparing. Insome embodiments, the device determines that the lower case Unicodevalue of the pivot element matches the corresponding lower case Unicodevalue of the character of the last character of the pattern The devicemay jump the pointer to the byte location in the block of text thatcorresponds to the beginning of the pattern and compares the patternagainst a corresponding portion of the block of text identified by thepointer.

In another aspect, the present disclosure is related to systems andmethods for simultaneously performing case insensitive searches ofvariable width encoded patterns in a block of text. A device may converteach of the patterns to be searched within a block of text to acorresponding lower case pattern, each pattern comprising variable-widthencoded characters. The device may establish for each of the patterns ashift table comprising a hash of a predetermined number of bytes of thecorresponding lower case pattern and a jump value. Responsive to theshift table, the device may jump or move a pointer to a pivot block inthe block of text. The device may identify an encoded string within thepivot block that comprises bytes from the predetermined number of bytesof the pivot block and compute a hash of the bytes of the lower case ofthe encoded string corresponding to the predetermined number of bytes.The device may obtain the jump value from the shift table using the hashof the bytes.

In some embodiments, the pattern comprises variable-width encodedcharacters that are UTF-8 encoded. In some embodiments, the devicemaintains a list of patterns that have zero jumps at each hash. In someembodiments, the device may initially jump the pointer to an initialpivot block based on a minimum byte length across each of the patterns.In some embodiments, the device identifies minimal valid encoded stringcomprising bytes from the predetermined number of bytes of the pivotblock.

In some embodiments, the device indentifies that the jump value is zero.The device may determine whether any patterns associated with the jumpvalue of zero match corresponding text in the block of text. For eachpattern the device may move the pointer to the block of text back anumber of byte lengths of the pattern. The device may determine that thepattern does not match a corresponding portion of text identified by thepointer responsive to identifying that the pointer is not a characterboundary. The device may determine the pattern to the text of the blockof text identified by the pointer responsive to identifying that thepointer is at a character boundary.

The details of various embodiments of the methods and systems describedherein are set forth in the accompanying drawings and the descriptionbelow.

BRIEF DESCRIPTION OF THE FIGURES

The foregoing and other objects, aspects, features, and advantages ofthe methods and systems described herein will become more apparent andbetter understood by referring to the following description taken inconjunction with the accompanying drawings, in which:

FIG. 1A is a block diagram of an embodiment of a network environment fora client to access a server via an appliance;

FIG. 1B is a block diagram of an embodiment of an environment fordelivering a computing environment from a server to a client via anappliance;

FIG. 1C is a block diagram of another embodiment of an environment fordelivering a computing environment from a server to a client via anappliance;

FIG. 1D is a block diagram of another embodiment of an environment fordelivering a computing environment from a server to a client via anappliance;

FIGS. 1E-1H are block diagrams of embodiments of a computing device;

FIG. 2A is a block diagram of an embodiment of an appliance forprocessing communications between a client and a server;

FIG. 2B is a block diagram of another embodiment of an appliance foroptimizing, accelerating, load-balancing and routing communicationsbetween a client and a server;

FIG. 3 is a block diagram of an embodiment of a client for communicatingwith a server via the appliance;

FIG. 4A is a block diagram of an embodiment of a virtualizationenvironment;

FIG. 4B is a block diagram of another embodiment of a virtualizationenvironment;

FIG. 4C is a block diagram of an embodiment of a virtualized appliance;

FIG. 5A are block diagrams of embodiments of approaches to implementingparallelism in a multi-core system;

FIG. 5B is a block diagram of an embodiment of a system utilizing amulti-core system;

FIG. 5C is a block diagram of another embodiment of an aspect of amulti-core system;

FIGS. 6A-6C are block diagrams of embodiments of a system for performingstreaming rewrites;

FIG. 7 is a flow diagram of an embodiment of a method for performingstreaming rewrites;

FIG. 8A is a flow diagram of an embodiment of a method for performingstreaming rewrites; and

FIG. 8B is a flow diagram of another embodiment of a method forperforming streaming rewrites;

FIG. 9A is a block diagram of an embodiment of a system for searchingvariable width encoded data;

FIG. 9B is a flow diagram of an embodiment of a method for searchingvariable width encoded data; and

FIG. 9C is a flow diagram of another embodiment of a method forsearching variable width encoded data.

The features and advantages of the methods and systems described hereinwill become more apparent from the detailed description set forth belowwhen taken in conjunction with the drawings, in which like referencecharacters identify corresponding elements throughout. In the drawings,like reference numbers generally indicate identical, functionallysimilar, and/or structurally similar elements.

DETAILED DESCRIPTION OF THE DISCLOSURE

For purposes of reading the description of the various embodimentsbelow, the following descriptions of the sections of the specificationand their respective contents may be helpful:

-   -   Section A describes a network environment and computing        environment which may be useful for practicing embodiments        described herein;    -   Section B describes embodiments of systems and methods for        delivering a computing environment to a remote user;    -   Section C describes embodiments of systems and methods for        accelerating communications between a client and a server;    -   Section D describes embodiments of systems and methods for        virtualizing an application delivery controller;    -   Section E describes embodiments of systems and methods for        providing a multi-core architecture and environment; and    -   Section F describes embodiments of systems and methods for        rewriting a stream of data via an intermediary.    -   Section G describes embodiments of systems and methods for        rewriting a stream of data containing UTF-8 encoding via an        intermediary.

A. Network and Computing Environment

Prior to discussing the specifics of embodiments of the systems andmethods of an appliance and/or client, it may be helpful to discuss thenetwork and computing environments in which such embodiments may bedeployed. Referring now to FIG. 1A, an embodiment of a networkenvironment is depicted. In brief overview, the network environmentcomprises one or more clients 102 a-102 n (also generally referred to aslocal machine(s) 102, or client(s) 102) in communication with one ormore servers 106 a-106 n (also generally referred to as server(s) 106,or remote machine(s) 106) via one or more networks 104, 104′ (generallyreferred to as network 104). In some embodiments, a client 102communicates with a server 106 via an appliance 200.

Although FIG. 1A shows a network 104 and a network 104′ between theclients 102 and the servers 106, the clients 102 and the servers 106 maybe on the same network 104. The networks 104 and 104′ can be the sametype of network or different types of networks. The network 104 and/orthe network 104′ can be a local-area network (LAN), such as a companyIntranet, a metropolitan area network (MAN), or a wide area network(WAN), such as the Internet or the World Wide Web. In one embodiment,network 104′ may be a private network and network 104 may be a publicnetwork. In some embodiments, network 104 may be a private network andnetwork 104′ a public network. In another embodiment, networks 104 and104′ may both be private networks. In some embodiments, clients 102 maybe located at a branch office of a corporate enterprise communicatingvia a WAN connection over the network 104 to the servers 106 located ata corporate data center.

The network 104 and/or 104′ be any type and/or form of network and mayinclude any of the following: a point to point network, a broadcastnetwork, a wide area network, a local area network, a telecommunicationsnetwork, a data communication network, a computer network, an ATM(Asynchronous Transfer Mode) network, a SONET (Synchronous OpticalNetwork) network, a SDH (Synchronous Digital Hierarchy) network, awireless network and a wireline network. In some embodiments, thenetwork 104 may comprise a wireless link, such as an infrared channel orsatellite band. The topology of the network 104 and/or 104′ may be abus, star, or ring network topology. The network 104 and/or 104′ andnetwork topology may be of any such network or network topology as knownto those ordinarily skilled in the art capable of supporting theoperations described herein.

As shown in FIG. 1A, the appliance 200, which also may be referred to asan interface unit 200 or gateway 200, is shown between the networks 104and 104′. In some embodiments, the appliance 200 may be located onnetwork 104. For example, a branch office of a corporate enterprise maydeploy an appliance 200 at the branch office. In other embodiments, theappliance 200 may be located on network 104′. For example, an appliance200 may be located at a corporate data center. In yet anotherembodiment, a plurality of appliances 200 may be deployed on network104. In some embodiments, a plurality of appliances 200 may be deployedon network 104′. In one embodiment, a first appliance 200 communicateswith a second appliance 200′. In other embodiments, the appliance 200could be a part of any client 102 or server 106 on the same or differentnetwork 104,104′ as the client 102. One or more appliances 200 may belocated at any point in the network or network communications pathbetween a client 102 and a server 106.

In some embodiments, the appliance 200 comprises any of the networkdevices manufactured by Citrix Systems, Inc. of Ft. Lauderdale Fla.,referred to as Citrix NetScaler devices. In other embodiments, theappliance 200 includes any of the product embodiments referred to asWebAccelerator and BigIP manufactured by F5 Networks, Inc. of Seattle,Wash. In another embodiment, the appliance 205 includes any of the DXacceleration device platforms and/or the SSL VPN series of devices, suchas SA 700, SA 2000, SA 4000, and SA 6000 devices manufactured by JuniperNetworks, Inc. of Sunnyvale, Calif. In yet another embodiment, theappliance 200 includes any application acceleration and/or securityrelated appliances and/or software manufactured by Cisco Systems, Inc.of San Jose, Calif., such as the Cisco ACE Application Control EngineModule service software and network modules, and Cisco AVS SeriesApplication Velocity System.

In one embodiment, the system may include multiple, logically-groupedservers 106. In these embodiments, the logical group of servers may bereferred to as a server farm 38. In some of these embodiments, theserves 106 may be geographically dispersed. In some cases, a farm 38 maybe administered as a single entity. In other embodiments, the serverfarm 38 comprises a plurality of server farms 38. In one embodiment, theserver farm executes one or more applications on behalf of one or moreclients 102.

The servers 106 within each farm 38 can be heterogeneous. One or more ofthe servers 106 can operate according to one type of operating systemplatform (e.g., WINDOWS NT, manufactured by Microsoft Corp. of Redmond,Wash.), while one or more of the other servers 106 can operate onaccording to another type of operating system platform (e.g., Unix orLinux). The servers 106 of each farm 38 do not need to be physicallyproximate to another server 106 in the same farm 38. Thus, the group ofservers 106 logically grouped as a farm 38 may be interconnected using awide-area network (WAN) connection or medium-area network (MAN)connection. For example, a farm 38 may include servers 106 physicallylocated in different continents or different regions of a continent,country, state, city, campus, or room. Data transmission speeds betweenservers 106 in the farm 38 can be increased if the servers 106 areconnected using a local-area network (LAN) connection or some form ofdirect connection.

Servers 106 may be referred to as a file server, application server, webserver, proxy server, or gateway server. In some embodiments, a server106 may have the capacity to function as either an application server oras a master application server. In one embodiment, a server 106 mayinclude an Active Directory. The clients 102 may also be referred to asclient nodes or endpoints. In some embodiments, a client 102 has thecapacity to function as both a client node seeking access toapplications on a server and as an application server providing accessto hosted applications for other clients 102 a-102 n.

In some embodiments, a client 102 communicates with a server 106. In oneembodiment, the client 102 communicates directly with one of the servers106 in a farm 38. In another embodiment, the client 102 executes aprogram neighborhood application to communicate with a server 106 in afarm 38. In still another embodiment, the server 106 provides thefunctionality of a master node. In some embodiments, the client 102communicates with the server 106 in the farm 38 through a network 104.Over the network 104, the client 102 can, for example, request executionof various applications hosted by the servers 106 a-106 n in the farm 38and receive output of the results of the application execution fordisplay. In some embodiments, only the master node provides thefunctionality required to identify and provide address informationassociated with a server 106′ hosting a requested application.

In one embodiment, the server 106 provides functionality of a webserver. In another embodiment, the server 106 a receives requests fromthe client 102, forwards the requests to a second server 106 b andresponds to the request by the client 102 with a response to the requestfrom the server 106 b. In still another embodiment, the server 106acquires an enumeration of applications available to the client 102 andaddress information associated with a server 106 hosting an applicationidentified by the enumeration of applications. In yet anotherembodiment, the server 106 presents the response to the request to theclient 102 using a web interface. In one embodiment, the client 102communicates directly with the server 106 to access the identifiedapplication. In another embodiment, the client 102 receives applicationoutput data, such as display data, generated by an execution of theidentified application on the server 106.

Referring now to FIG. 1B, an embodiment of a network environmentdeploying multiple appliances 200 is depicted. A first appliance 200 maybe deployed on a first network 104 and a second appliance 200′ on asecond network 104′. For example a corporate enterprise may deploy afirst appliance 200 at a branch office and a second appliance 200′ at adata center. In another embodiment, the first appliance 200 and secondappliance 200′ are deployed on the same network 104 or network 104. Forexample, a first appliance 200 may be deployed for a first server farm38, and a second appliance 200 may be deployed for a second server farm38′. In another example, a first appliance 200 may be deployed at afirst branch office while the second appliance 200′ is deployed at asecond branch office′. In some embodiments, the first appliance 200 andsecond appliance 200′ work in cooperation or in conjunction with eachother to accelerate network traffic or the delivery of application anddata between a client and a server

Referring now to FIG. 1C, another embodiment of a network environmentdeploying the appliance 200 with one or more other types of appliances,such as between one or more WAN optimization appliance 205, 205′ isdepicted. For example a first WAN optimization appliance 205 is shownbetween networks 104 and 104′ and s second WAN optimization appliance205′ may be deployed between the appliance 200 and one or more servers106. By way of example, a corporate enterprise may deploy a first WANoptimization appliance 205 at a branch office and a second WANoptimization appliance 205′ at a data center. In some embodiments, theappliance 205 may be located on network 104′. In other embodiments, theappliance 205′ may be located on network 104. In some embodiments, theappliance 205′ may be located on network 104′ or network 104″. In oneembodiment, the appliance 205 and 205′ are on the same network. Inanother embodiment, the appliance 205 and 205′ are on differentnetworks. In another example, a first WAN optimization appliance 205 maybe deployed for a first server farm 38 and a second WAN optimizationappliance 205′ for a second server farm 38′

In one embodiment, the appliance 205 is a device for accelerating,optimizing or otherwise improving the performance, operation, or qualityof service of any type and form of network traffic, such as traffic toand/or from a WAN connection. In some embodiments, the appliance 205 isa performance enhancing proxy. In other embodiments, the appliance 205is any type and form of WAN optimization or acceleration device,sometimes also referred to as a WAN optimization controller. In oneembodiment, the appliance 205 is any of the product embodiments referredto as WANScaler manufactured by Citrix Systems, Inc. of Ft. Lauderdale,Fla. In other embodiments, the appliance 205 includes any of the productembodiments referred to as BIG-IP link controller and WANjetmanufactured by F5 Networks, Inc. of Seattle, Wash. In anotherembodiment, the appliance 205 includes any of the WX and WXC WANacceleration device platforms manufactured by Juniper Networks, Inc. ofSunnyvale, Calif. In some embodiments, the appliance 205 includes any ofthe steelhead line of WAN optimization appliances manufactured byRiverbed Technology of San Francisco, Calif. In other embodiments, theappliance 205 includes any of the WAN related devices manufactured byExpand Networks Inc. of Roseland, N.J. In one embodiment, the appliance205 includes any of the WAN related appliances manufactured by PacketeerInc. of Cupertino, Calif., such as the PacketShaper, iShared, and SkyXproduct embodiments provided by Packeteer. In yet another embodiment,the appliance 205 includes any WAN related appliances and/or softwaremanufactured by Cisco Systems, Inc. of San Jose, Calif., such as theCisco Wide Area Network Application Services software and networkmodules, and Wide Area Network engine appliances.

In one embodiment, the appliance 205 provides application and dataacceleration services for branch-office or remote offices. In oneembodiment, the appliance 205 includes optimization of Wide Area FileServices (WAFS). In another embodiment, the appliance 205 acceleratesthe delivery of files, such as via the Common Internet File System(CIFS) protocol. In other embodiments, the appliance 205 providescaching in memory and/or storage to accelerate delivery of applicationsand data. In one embodiment, the appliance 205 provides compression ofnetwork traffic at any level of the network stack or at any protocol ornetwork layer. In another embodiment, the appliance 205 providestransport layer protocol optimizations, flow control, performanceenhancements or modifications and/or management to accelerate deliveryof applications and data over a WAN connection. For example, in oneembodiment, the appliance 205 provides Transport Control Protocol (TCP)optimizations. In other embodiments, the appliance 205 providesoptimizations, flow control, performance enhancements or modificationsand/or management for any session or application layer protocol.

In another embodiment, the appliance 205 encoded any type and form ofdata or information into custom or standard TCP and/or IP header fieldsor option fields of network packet to announce presence, functionalityor capability to another appliance 205′. In another embodiment, anappliance 205′ may communicate with another appliance 205′ using dataencoded in both TCP and/or IP header fields or options. For example, theappliance may use TCP option(s) or IP header fields or options tocommunicate one or more parameters to be used by the appliances 205,205′ in performing functionality, such as WAN acceleration, or forworking in conjunction with each other.

In some embodiments, the appliance 200 preserves any of the informationencoded in TCP and/or IP header and/or option fields communicatedbetween appliances 205 and 205′. For example, the appliance 200 mayterminate a transport layer connection traversing the appliance 200,such as a transport layer connection from between a client and a servertraversing appliances 205 and 205′. In one embodiment, the appliance 200identifies and preserves any encoded information in a transport layerpacket transmitted by a first appliance 205 via a first transport layerconnection and communicates a transport layer packet with the encodedinformation to a second appliance 205′ via a second transport layerconnection.

Referring now to FIG. 1D, a network environment for delivering and/oroperating a computing environment on a client 102 is depicted. In someembodiments, a server 106 includes an application delivery system 190for delivering a computing environment or an application and/or datafile to one or more clients 102. In brief overview, a client 10 is incommunication with a server 106 via network 104, 104′ and appliance 200.For example, the client 102 may reside in a remote office of a company,e.g., a branch office, and the server 106 may reside at a corporate datacenter. The client 102 comprises a client agent 120, and a computingenvironment 15. The computing environment 15 may execute or operate anapplication that accesses, processes or uses a data file. The computingenvironment 15, application and/or data file may be delivered via theappliance 200 and/or the server 106.

In some embodiments, the appliance 200 accelerates delivery of acomputing environment 15, or any portion thereof, to a client 102. Inone embodiment, the appliance 200 accelerates the delivery of thecomputing environment 15 by the application delivery system 190. Forexample, the embodiments described herein may be used to acceleratedelivery of a streaming application and data file processable by theapplication from a central corporate data center to a remote userlocation, such as a branch office of the company. In another embodiment,the appliance 200 accelerates transport layer traffic between a client102 and a server 106. The appliance 200 may provide accelerationtechniques for accelerating any transport layer payload from a server106 to a client 102, such as: 1) transport layer connection pooling, 2)transport layer connection multiplexing, 3) transport control protocolbuffering, 4) compression and 5) caching. In some embodiments, theappliance 200 provides load balancing of servers 106 in responding torequests from clients 102. In other embodiments, the appliance 200 actsas a proxy or access server to provide access to the one or more servers106. In another embodiment, the appliance 200 provides a secure virtualprivate network connection from a first network 104 of the client 102 tothe second network 104′ of the server 106, such as an SSL VPNconnection. It yet other embodiments, the appliance 200 providesapplication firewall security, control and management of the connectionand communications between a client 102 and a server 106.

In some embodiments, the application delivery management system 190provides application delivery techniques to deliver a computingenvironment to a desktop of a user, remote or otherwise, based on aplurality of execution methods and based on any authentication andauthorization policies applied via a policy engine 195. With thesetechniques, a remote user may obtain a computing environment and accessto server stored applications and data files from any network connecteddevice 100. In one embodiment, the application delivery system 190 mayreside or execute on a server 106. In another embodiment, theapplication delivery system 190 may reside or execute on a plurality ofservers 106 a-106 n. In some embodiments, the application deliverysystem 190 may execute in a server farm 38. In one embodiment, theserver 106 executing the application delivery system 190 may also storeor provide the application and data file. In another embodiment, a firstset of one or more servers 106 may execute the application deliverysystem 190, and a different server 106 n may store or provide theapplication and data file. In some embodiments, each of the applicationdelivery system 190, the application, and data file may reside or belocated on different servers. In yet another embodiment, any portion ofthe application delivery system 190 may reside, execute or be stored onor distributed to the appliance 200, or a plurality of appliances.

The client 102 may include a computing environment 15 for executing anapplication that uses or processes a data file. The client 102 vianetworks 104, 104′ and appliance 200 may request an application and datafile from the server 106. In one embodiment, the appliance 200 mayforward a request from the client 102 to the server 106. For example,the client 102 may not have the application and data file stored oraccessible locally. In response to the request, the application deliverysystem 190 and/or server 106 may deliver the application and data fileto the client 102. For example, in one embodiment, the server 106 maytransmit the application as an application stream to operate incomputing environment 15 on client 102.

In some embodiments, the application delivery system 190 comprises anyportion of the Citrix Access Suite™ by Citrix Systems, Inc., such as theMetaFrame or Citrix Presentation Server™ and/or any of the Microsoft®Windows Terminal Services manufactured by the Microsoft Corporation. Inone embodiment, the application delivery system 190 may deliver one ormore applications to clients 102 or users via a remote-display protocolor otherwise via remote-based or server-based computing. In anotherembodiment, the application delivery system 190 may deliver one or moreapplications to clients or users via steaming of the application.

In one embodiment, the application delivery system 190 includes a policyengine 195 for controlling and managing the access to, selection ofapplication execution methods and the delivery of applications. In someembodiments, the policy engine 195 determines the one or moreapplications a user or client 102 may access. In another embodiment, thepolicy engine 195 determines how the application should be delivered tothe user or client 102, e.g., the method of execution. In someembodiments, the application delivery system 190 provides a plurality ofdelivery techniques from which to select a method of applicationexecution, such as a server-based computing, streaming or delivering theapplication locally to the client 120 for local execution.

In one embodiment, a client 102 requests execution of an applicationprogram and the application delivery system 190 comprising a server 106selects a method of executing the application program. In someembodiments, the server 106 receives credentials from the client 102. Inanother embodiment, the server 106 receives a request for an enumerationof available applications from the client 102. In one embodiment, inresponse to the request or receipt of credentials, the applicationdelivery system 190 enumerates a plurality of application programsavailable to the client 102. The application delivery system 190receives a request to execute an enumerated application. The applicationdelivery system 190 selects one of a predetermined number of methods forexecuting the enumerated application, for example, responsive to apolicy of a policy engine. The application delivery system 190 mayselect a method of execution of the application enabling the client 102to receive application-output data generated by execution of theapplication program on a server 106. The application delivery system 190may select a method of execution of the application enabling the localmachine 10 to execute the application program locally after retrieving aplurality of application files comprising the application. In yetanother embodiment, the application delivery system 190 may select amethod of execution of the application to stream the application via thenetwork 104 to the client 102.

A client 102 may execute, operate or otherwise provide an application,which can be any type and/or form of software, program, or executableinstructions such as any type and/or form of web browser, web-basedclient, client-server application, a thin-client computing client, anActiveX control, or a Java applet, or any other type and/or form ofexecutable instructions capable of executing on client 102. In someembodiments, the application may be a server-based or a remote-basedapplication executed on behalf of the client 102 on a server 106. In oneembodiments the server 106 may display output to the client 102 usingany thin-client or remote-display protocol, such as the IndependentComputing Architecture (ICA) protocol manufactured by Citrix Systems,Inc. of Ft. Lauderdale, Fla. or the Remote Desktop Protocol (RDP)manufactured by the Microsoft Corporation of Redmond, Wash. Theapplication can use any type of protocol and it can be, for example, anHTTP client, an FTP client, an Oscar client, or a Telnet client. Inother embodiments, the application comprises any type of softwarerelated to VoIP communications, such as a soft IP telephone. In furtherembodiments, the application comprises any application related toreal-time data communications, such as applications for streaming videoand/or audio.

In some embodiments, the server 106 or a server farm 38 may be runningone or more applications, such as an application providing a thin-clientcomputing or remote display presentation application. In one embodiment,the server 106 or server farm 38 executes as an application, any portionof the Citrix Access Suite™ by Citrix Systems, Inc., such as theMetaFrame or Citrix Presentation Server™, and/or any of the Microsoft®Windows Terminal Services manufactured by the Microsoft Corporation. Inone embodiment, the application is an ICA client, developed by CitrixSystems, Inc. of Fort Lauderdale, Fla. In other embodiments, theapplication includes a Remote Desktop (RDP) client, developed byMicrosoft Corporation of Redmond, Wash. Also, the server 106 may run anapplication, which for example, may be an application server providingemail services such as Microsoft Exchange manufactured by the MicrosoftCorporation of Redmond, Wash., a web or Internet server, or a desktopsharing server, or a collaboration server.

In some embodiments, any of the applications may comprise any type ofhosted service or products, such as GoToMeeting™ provided by CitrixOnline Division, Inc. of Santa Barbara, Calif., WebEx™ provided byWebEx, Inc. of Santa Clara, Calif., or Microsoft Office Live Meetingprovided by Microsoft Corporation of Redmond, Wash.

Still referring to FIG. 1D, an embodiment of the network environment mayinclude a monitoring server 106A. The monitoring server 106A may includeany type and form performance monitoring service 198. The performancemonitoring service 198 may include monitoring, measurement and/ormanagement software and/or hardware, including data collection,aggregation, analysis, management and reporting. In one embodiment, theperformance monitoring service 198 includes one or more monitoringagents 197. The monitoring agent 197 includes any software, hardware orcombination thereof for performing monitoring, measurement and datacollection activities on a device, such as a client 102, server 106 oran appliance 200, 205. In some embodiments, the monitoring agent 197includes any type and form of script, such as Visual Basic script, orJavascript. In one embodiment, the monitoring agent 197 executestransparently to any application and/or user of the device. In someembodiments, the monitoring agent 197 is installed and operatedunobtrusively to the application or client. In yet another embodiment,the monitoring agent 197 is installed and operated without anyinstrumentation for the application or device.

In some embodiments, the monitoring agent 197 monitors, measures andcollects data on a predetermined frequency. In other embodiments, themonitoring agent 197 monitors, measures and collects data based upondetection of any type and form of event. For example, the monitoringagent 197 may collect data upon detection of a request for a web page orreceipt of an HTTP response. In another example, the monitoring agent197 may collect data upon detection of any user input events, such as amouse click. The monitoring agent 197 may report or provide anymonitored, measured or collected data to the monitoring service 198. Inone embodiment, the monitoring agent 197 transmits information to themonitoring service 198 according to a schedule or a predeterminedfrequency. In another embodiment, the monitoring agent 197 transmitsinformation to the monitoring service 198 upon detection of an event.

In some embodiments, the monitoring service 198 and/or monitoring agent197 performs monitoring and performance measurement of any networkresource or network infrastructure element, such as a client, server,server farm, appliance 200, appliance 205, or network connection. In oneembodiment, the monitoring service 198 and/or monitoring agent 197performs monitoring and performance measurement of any transport layerconnection, such as a TCP or UDP connection. In another embodiment, themonitoring service 198 and/or monitoring agent 197 monitors and measuresnetwork latency. In yet one embodiment, the monitoring service 198and/or monitoring agent 197 monitors and measures bandwidth utilization.

In other embodiments, the monitoring service 198 and/or monitoring agent197 monitors and measures end-user response times. In some embodiments,the monitoring service 198 performs monitoring and performancemeasurement of an application. In another embodiment, the monitoringservice 198 and/or monitoring agent 197 performs monitoring andperformance measurement of any session or connection to the application.In one embodiment, the monitoring service 198 and/or monitoring agent197 monitors and measures performance of a browser. In anotherembodiment, the monitoring service 198 and/or monitoring agent 197monitors and measures performance of HTTP based transactions. In someembodiments, the monitoring service 198 and/or monitoring agent 197monitors and measures performance of a Voice over IP (VoIP) applicationor session. In other embodiments, the monitoring service 198 and/ormonitoring agent 197 monitors and measures performance of a remotedisplay protocol application, such as an ICA client or RDP client. Inyet another embodiment, the monitoring service 198 and/or monitoringagent 197 monitors and measures performance of any type and form ofstreaming media. In still a further embodiment, the monitoring service198 and/or monitoring agent 197 monitors and measures performance of ahosted application or a Software-As-A-Service (SaaS) delivery model.

In some embodiments, the monitoring service 198 and/or monitoring agent197 performs monitoring and performance measurement of one or moretransactions, requests or responses related to application. In otherembodiments, the monitoring service 198 and/or monitoring agent 197monitors and measures any portion of an application layer stack, such asany .NET or J2EE calls. In one embodiment, the monitoring service 198and/or monitoring agent 197 monitors and measures database or SQLtransactions. In yet another embodiment, the monitoring service 198and/or monitoring agent 197 monitors and measures any method, functionor application programming interface (API) call.

In one embodiment, the monitoring service 198 and/or monitoring agent197 performs monitoring and performance measurement of a delivery ofapplication and/or data from a server to a client via one or moreappliances, such as appliance 200 and/or appliance 205. In someembodiments, the monitoring service 198 and/or monitoring agent 197monitors and measures performance of delivery of a virtualizedapplication. In other embodiments, the monitoring service 198 and/ormonitoring agent 197 monitors and measures performance of delivery of astreaming application. In another embodiment, the monitoring service 198and/or monitoring agent 197 monitors and measures performance ofdelivery of a desktop application to a client and/or the execution ofthe desktop application on the client. In another embodiment, themonitoring service 198 and/or monitoring agent 197 monitors and measuresperformance of a client/server application.

In one embodiment, the monitoring service 198 and/or monitoring agent197 is designed and constructed to provide application performancemanagement for the application delivery system 190. For example, themonitoring service 198 and/or monitoring agent 197 may monitor, measureand manage the performance of the delivery of applications via theCitrix Presentation Server. In this example, the monitoring service 198and/or monitoring agent 197 monitors individual ICA sessions. Themonitoring service 198 and/or monitoring agent 197 may measure the totaland per session system resource usage, as well as application andnetworking performance. The monitoring service 198 and/or monitoringagent 197 may identify the active servers for a given user and/or usersession. In some embodiments, the monitoring service 198 and/ormonitoring agent 197 monitors back-end connections between theapplication delivery system 190 and an application and/or databaseserver. The monitoring service 198 and/or monitoring agent 197 maymeasure network latency, delay and volume per user-session or ICAsession.

In some embodiments, the monitoring service 198 and/or monitoring agent197 measures and monitors memory usage for the application deliverysystem 190, such as total memory usage, per user session and/or perprocess. In other embodiments, the monitoring service 198 and/ormonitoring agent 197 measures and monitors CPU usage the applicationdelivery system 190, such as total CPU usage, per user session and/orper process. In another embodiments, the monitoring service 198 and/ormonitoring agent 197 measures and monitors the time required to log-into an application, a server, or the application delivery system, such asCitrix Presentation Server. In one embodiment, the monitoring service198 and/or monitoring agent 197 measures and monitors the duration auser is logged into an application, a server, or the applicationdelivery system 190. In some embodiments, the monitoring service 198and/or monitoring agent 197 measures and monitors active and inactivesession counts for an application, server or application delivery systemsession. In yet another embodiment, the monitoring service 198 and/ormonitoring agent 197 measures and monitors user session latency.

In yet further embodiments, the monitoring service 198 and/or monitoringagent 197 measures and monitors measures and monitors any type and formof server metrics. In one embodiment, the monitoring service 198 and/ormonitoring agent 197 measures and monitors metrics related to systemmemory, CPU usage, and disk storage. In another embodiment, themonitoring service 198 and/or monitoring agent 197 measures and monitorsmetrics related to page faults, such as page faults per second. In otherembodiments, the monitoring service 198 and/or monitoring agent 197measures and monitors round-trip time metrics. In yet anotherembodiment, the monitoring service 198 and/or monitoring agent 197measures and monitors metrics related to application crashes, errorsand/or hangs.

In some embodiments, the monitoring service 198 and monitoring agent 198includes any of the product embodiments referred to as EdgeSightmanufactured by Citrix Systems, Inc. of Ft. Lauderdale, Fla. In anotherembodiment, the performance monitoring service 198 and/or monitoringagent 198 includes any portion of the product embodiments referred to asthe TrueView product suite manufactured by the Symphoniq Corporation ofPalo Alto, Calif. In one embodiment, the performance monitoring service198 and/or monitoring agent 198 includes any portion of the productembodiments referred to as the TeaLeaf CX product suite manufactured bythe TeaLeaf Technology Inc. of San Francisco, Calif. In otherembodiments, the performance monitoring service 198 and/or monitoringagent 198 includes any portion of the business service managementproducts, such as the BMC Performance Manager and Patrol products,manufactured by BMC Software, Inc. of Houston, Tex.

The client 102, server 106, and appliance 200 may be deployed as and/orexecuted on any type and form of computing device, such as a computer,network device or appliance capable of communicating on any type andform of network and performing the operations described herein. FIGS. 1Eand 1F depict block diagrams of a computing device 100 useful forpracticing an embodiment of the client 102, server 106 or appliance 200.As shown in FIGS. 1E and 1F, each computing device 100 includes acentral processing unit 101, and a main memory unit 122. As shown inFIG. 1E, a computing device 100 may include a visual display device 124,a keyboard 126 and/or a pointing device 127, such as a mouse. Eachcomputing device 100 may also include additional optional elements, suchas one or more input/output devices 130 a-130 b (generally referred tousing reference numeral 130), and a cache memory 140 in communicationwith the central processing unit 101.

The central processing unit 101 is any logic circuitry that responds toand processes instructions fetched from the main memory unit 122. Inmany embodiments, the central processing unit is provided by amicroprocessor unit, such as: those manufactured by Intel Corporation ofMountain View, Calif.; those manufactured by Motorola Corporation ofSchaumburg, Ill.; those manufactured by Transmeta Corporation of SantaClara, Calif.; the RS/6000 processor, those manufactured byInternational Business Machines of White Plains, N.Y.; or thosemanufactured by Advanced Micro Devices of Sunnyvale, Calif. Thecomputing device 100 may be based on any of these processors, or anyother processor capable of operating as described herein.

Main memory unit 122 may be one or more memory chips capable of storingdata and allowing any storage location to be directly accessed by themicroprocessor 101, such as Static random access memory (SRAM), BurstSRAM or SynchBurst SRAM (BSRAM), Dynamic random access memory (DRAM),Fast Page Mode DRAM (FPM DRAM), Enhanced DRAM (EDRAM), Extended DataOutput RAM (EDO RAM), Extended Data Output DRAM (EDO DRAM), BurstExtended Data Output DRAM (BEDO DRAM), Enhanced DRAM (EDRAM),synchronous DRAM (SDRAM), JEDEC SRAM, PC 100 SDRAM, Double Data RateSDRAM (DDR SDRAM), Enhanced SDRAM (ESDRAM), SyncLink DRAM (SLDRAM),Direct Rambus DRAM (DRDRAM), or Ferroelectric RAM (FRAM). The mainmemory 122 may be based on any of the above described memory chips, orany other available memory chips capable of operating as describedherein. In the embodiment shown in FIG. 1E, the processor 101communicates with main memory 122 via a system bus 150 (described inmore detail below). FIG. 1E depicts an embodiment of a computing device100 in which the processor communicates directly with main memory 122via a memory port 103. For example, in FIG. 1F the main memory 122 maybe DRDRAM.

FIG. 1F depicts an embodiment in which the main processor 101communicates directly with cache memory 140 via a secondary bus,sometimes referred to as a backside bus. In other embodiments, the mainprocessor 101 communicates with cache memory 140 using the system bus150. Cache memory 140 typically has a faster response time than mainmemory 122 and is typically provided by SRAM, BSRAM, or EDRAM. In theembodiment shown in FIG. 1E, the processor 101 communicates with variousI/O devices 130 via a local system bus 150. Various busses may be usedto connect the central processing unit 101 to any of the I/O devices130, including a VESA VL bus, an ISA bus, an EISA bus, a MicroChannelArchitecture (MCA) bus, a PCI bus, a PCI-X bus, a PCI-Express bus, or aNuBus. For embodiments in which the I/O device is a video display 124,the processor 101 may use an Advanced Graphics Port (AGP) to communicatewith the display 124. FIG. 1F depicts an embodiment of a computer 100 inwhich the main processor 101 communicates directly with I/O device 130via HyperTransport, Rapid I/O, or InfiniBand. FIG. 1F also depicts anembodiment in which local busses and direct communication are mixed: theprocessor 101 communicates with I/O device 130 using a localinterconnect bus while communicating with I/O device 130 directly.

The computing device 100 may support any suitable installation device116, such as a floppy disk drive for receiving floppy disks such as3.5-inch, 5.25-inch disks or ZIP disks, a CD-ROM drive, a CD-R/RW drive,a DVD-ROM drive, tape drives of various formats, USB device, hard-driveor any other device suitable for installing software and programs suchas any client agent 120, or portion thereof. The computing device 100may further comprise a storage device 128, such as one or more hard diskdrives or redundant arrays of independent disks, for storing anoperating system and other related software, and for storing applicationsoftware programs such as any program related to the client agent 120.Optionally, any of the installation devices 116 could also be used asthe storage device 128. Additionally, the operating system and thesoftware can be run from a bootable medium, for example, a bootable CD,such as KNOPPIX®, a bootable CD for GNU/Linux that is available as aGNU/Linux distribution from knoppix.net.

Furthermore, the computing device 100 may include a network interface118 to interface to a Local Area Network (LAN), Wide Area Network (WAN)or the Internet through a variety of connections including, but notlimited to, standard telephone lines, LAN or WAN links (e.g., 802.11,T1, T3, 56 kb, X.25), broadband connections (e.g., ISDN, Frame Relay,ATM), wireless connections, or some combination of any or all of theabove. The network interface 118 may comprise a built-in networkadapter, network interface card, PCMCIA network card, card bus networkadapter, wireless network adapter, USB network adapter, modem or anyother device suitable for interfacing the computing device 100 to anytype of network capable of communication and performing the operationsdescribed herein.

A wide variety of I/O devices 130 a-130 n may be present in thecomputing device 100. Input devices include keyboards, mice, trackpads,trackballs, microphones, and drawing tablets. Output devices includevideo displays, speakers, inkjet printers, laser printers, anddye-sublimation printers. The I/O devices 130 may be controlled by anI/O controller 123 as shown in FIG. 1E. The I/O controller may controlone or more I/O devices such as a keyboard 126 and a pointing device127, e.g., a mouse or optical pen. Furthermore, an I/O device may alsoprovide storage 128 and/or an installation medium 116 for the computingdevice 100. In still other embodiments, the computing device 100 mayprovide USB connections to receive handheld USB storage devices such asthe USB Flash Drive line of devices manufactured by Twintech Industry,Inc. of Los Alamitos, Calif.

In some embodiments, the computing device 100 may comprise or beconnected to multiple display devices 124 a-124 n, which each may be ofthe same or different type and/or form. As such, any of the I/O devices130 a-130 n and/or the I/O controller 123 may comprise any type and/orform of suitable hardware, software, or combination of hardware andsoftware to support, enable or provide for the connection and use ofmultiple display devices 124 a-124 n by the computing device 100. Forexample, the computing device 100 may include any type and/or form ofvideo adapter, video card, driver, and/or library to interface,communicate, connect or otherwise use the display devices 124 a-124 n.In one embodiment, a video adapter may comprise multiple connectors tointerface to multiple display devices 124 a-124 n. In other embodiments,the computing device 100 may include multiple video adapters, with eachvideo adapter connected to one or more of the display devices 124 a-124n. In some embodiments, any portion of the operating system of thecomputing device 100 may be configured for using multiple displays 124a-124 n. In other embodiments, one or more of the display devices 124a-124 n may be provided by one or more other computing devices, such ascomputing devices 100 a and 100 b connected to the computing device 100,for example, via a network. These embodiments may include any type ofsoftware designed and constructed to use another computer's displaydevice as a second display device 124 a for the computing device 100.One ordinarily skilled in the art will recognize and appreciate thevarious ways and embodiments that a computing device 100 may beconfigured to have multiple display devices 124 a-124 n.

In further embodiments, an I/O device 130 may be a bridge 170 betweenthe system bus 150 and an external communication bus, such as a USB bus,an Apple Desktop Bus, an RS-232 serial connection, a SCSI bus, aFireWire bus, a FireWire 800 bus, an Ethernet bus, an AppleTalk bus, aGigabit Ethernet bus, an Asynchronous Transfer Mode bus, a HIPPI bus, aSuper HIPPI bus, a SerialPlus bus, a SCI/LAMP bus, a FibreChannel bus,or a Serial Attached small computer system interface bus.

A computing device 100 of the sort depicted in FIGS. 1E and 1F typicallyoperate under the control of operating systems, which control schedulingof tasks and access to system resources. The computing device 100 can berunning any operating system such as any of the versions of theMicrosoft® Windows operating systems, the different releases of the Unixand Linux operating systems, any version of the Mac OS® for Macintoshcomputers, any embedded operating system, any real-time operatingsystem, any open source operating system, any proprietary operatingsystem, any operating systems for mobile computing devices, or any otheroperating system capable of running on the computing device andperforming the operations described herein. Typical operating systemsinclude: WINDOWS 3.x, WINDOWS 95, WINDOWS 98, WINDOWS 2000, WINDOWS NT3.51, WINDOWS NT 4.0, WINDOWS CE, and WINDOWS XP, all of which aremanufactured by Microsoft Corporation of Redmond, Wash.; MacOS,manufactured by Apple Computer of Cupertino, Calif.; OS/2, manufacturedby International Business Machines of Armonk, N.Y.; and Linux, afreely-available operating system distributed by Caldera Corp. of SaltLake City, Utah, or any type and/or form of a Unix operating system,among others.

In other embodiments, the computing device 100 may have differentprocessors, operating systems, and input devices consistent with thedevice. For example, in one embodiment the computer 100 is a Treo 180,270, 1060, 600 or 650 smart phone manufactured by Palm, Inc. In thisembodiment, the Treo smart phone is operated under the control of thePalmOS operating system and includes a stylus input device as well as afive-way navigator device. Moreover, the computing device 100 can be anyworkstation, desktop computer, laptop or notebook computer, server,handheld computer, mobile telephone, any other computer, or other formof computing or telecommunications device that is capable ofcommunication and that has sufficient processor power and memorycapacity to perform the operations described herein.

As shown in FIG. 1G, the computing device 100 may comprise multipleprocessors and may provide functionality for simultaneous execution ofinstructions or for simultaneous execution of one instruction on morethan one piece of data. In some embodiments, the computing device 100may comprise a parallel processor with one or more cores. In one ofthese embodiments, the computing device 100 is a shared memory paralleldevice, with multiple processors and/or multiple processor cores,accessing all available memory as a single global address space. Inanother of these embodiments, the computing device 100 is a distributedmemory parallel device with multiple processors each accessing localmemory only. In still another of these embodiments, the computing device100 has both some memory which is shared and some memory which can onlybe accessed by particular processors or subsets of processors. In stilleven another of these embodiments, the computing device 100, such as amulti-core microprocessor, combines two or more independent processorsinto a single package, often a single integrated circuit (IC). In yetanother of these embodiments, the computing device 100 includes a chiphaving a CELL BROADBAND ENGINE architecture and including a Powerprocessor element and a plurality of synergistic processing elements,the Power processor element and the plurality of synergistic processingelements linked together by an internal high speed bus, which may bereferred to as an element interconnect bus.

In some embodiments, the processors provide functionality for executionof a single instruction simultaneously on multiple pieces of data(SIMD). In other embodiments, the processors provide functionality forexecution of multiple instructions simultaneously on multiple pieces ofdata (MIMD). In still other embodiments, the processor may use anycombination of SIMD and MIMD cores in a single device.

In some embodiments, the computing device 100 may comprise a graphicsprocessing unit. In one of these embodiments, depicted in FIG. 1H, thecomputing device 100 includes at least one central processing unit 101and at least one graphics processing unit. In another of theseembodiments, the computing device 100 includes at least one parallelprocessing unit and at least one graphics processing unit. In stillanother of these embodiments, the computing device 100 includes aplurality of processing units of any type, one of the plurality ofprocessing units comprising a graphics processing unit.

In some embodiments, a first computing device 100 a executes anapplication on behalf of a user of a client computing device 100 b. Inother embodiments, a computing device 100 a executes a virtual machine,which provides an execution session within which applications execute onbehalf of a user or a client computing devices 100 b. In one of theseembodiments, the execution session is a hosted desktop session. Inanother of these embodiments, the computing device 100 executes aterminal services session. The terminal services session may provide ahosted desktop environment. In still another of these embodiments, theexecution session provides access to a computing environment, which maycomprise one or more of: an application, a plurality of applications, adesktop application, and a desktop session in which one or moreapplications may execute.

B. Appliance Architecture

FIG. 2A illustrates an example embodiment of the appliance 200. Thearchitecture of the appliance 200 in FIG. 2A is provided by way ofillustration only and is not intended to be limiting. As shown in FIG.2, appliance 200 comprises a hardware layer 206 and a software layerdivided into a user space 202 and a kernel space 204.

Hardware layer 206 provides the hardware elements upon which programsand services within kernel space 204 and user space 202 are executed.Hardware layer 206 also provides the structures and elements which allowprograms and services within kernel space 204 and user space 202 tocommunicate data both internally and externally with respect toappliance 200. As shown in FIG. 2, the hardware layer 206 includes aprocessing unit 262 for executing software programs and services, amemory 264 for storing software and data, network ports 266 fortransmitting and receiving data over a network, and an encryptionprocessor 260 for performing functions related to Secure Sockets Layerprocessing of data transmitted and received over the network. In someembodiments, the central processing unit 262 may perform the functionsof the encryption processor 260 in a single processor. Additionally, thehardware layer 206 may comprise multiple processors for each of theprocessing unit 262 and the encryption processor 260. The processor 262may include any of the processors 101 described above in connection withFIGS. 1E and 1F. For example, in one embodiment, the appliance 200comprises a first processor 262 and a second processor 262′. In otherembodiments, the processor 262 or 262′ comprises a multi-core processor.

Although the hardware layer 206 of appliance 200 is generallyillustrated with an encryption processor 260, processor 260 may be aprocessor for performing functions related to any encryption protocol,such as the Secure Socket Layer (SSL) or Transport Layer Security (TLS)protocol. In some embodiments, the processor 260 may be a generalpurpose processor (GPP), and in further embodiments, may have executableinstructions for performing processing of any security related protocol.

Although the hardware layer 206 of appliance 200 is illustrated withcertain elements in FIG. 2, the hardware portions or components ofappliance 200 may comprise any type and form of elements, hardware orsoftware, of a computing device, such as the computing device 100illustrated and discussed herein in conjunction with FIGS. 1E and 1F. Insome embodiments, the appliance 200 may comprise a server, gateway,router, switch, bridge or other type of computing or network device, andhave any hardware and/or software elements associated therewith.

The operating system of appliance 200 allocates, manages, or otherwisesegregates the available system memory into kernel space 204 and userspace 204. In example software architecture 200, the operating systemmay be any type and/or form of Unix operating system although themethods and systems described herein are not so limited. As such, theappliance 200 can be running any operating system such as any of theversions of the Microsoft® Windows operating systems, the differentreleases of the Unix and Linux operating systems, any version of the MacOS® for Macintosh computers, any embedded operating system, any networkoperating system, any real-time operating system, any open sourceoperating system, any proprietary operating system, any operatingsystems for mobile computing devices or network devices, or any otheroperating system capable of running on the appliance 200 and performingthe operations described herein.

The kernel space 204 is reserved for running the kernel 230, includingany device drivers, kernel extensions or other kernel related software.As known to those skilled in the art, the kernel 230 is the core of theoperating system, and provides access, control, and management ofresources and hardware-related elements of the application 104. Inaccordance with an embodiment of the appliance 200, the kernel space 204also includes a number of network services or processes working inconjunction with a cache manager 232, sometimes also referred to as theintegrated cache, the benefits of which are described in detail furtherherein. Additionally, the embodiment of the kernel 230 will depend onthe embodiment of the operating system installed, configured, orotherwise used by the device 200.

In one embodiment, the device 200 comprises one network stack 267, suchas a TCP/IP based stack, for communicating with the client 102 and/orthe server 106. In one embodiment, the network stack 267 is used tocommunicate with a first network, such as network 108, and a secondnetwork 110. In some embodiments, the device 200 terminates a firsttransport layer connection, such as a TCP connection of a client 102,and establishes a second transport layer connection to a server 106 foruse by the client 102, e.g., the second transport layer connection isterminated at the appliance 200 and the server 106. The first and secondtransport layer connections may be established via a single networkstack 267. In other embodiments, the device 200 may comprise multiplenetwork stacks, for example 267 and 267′, and the first transport layerconnection may be established or terminated at one network stack 267,and the second transport layer connection on the second network stack267′. For example, one network stack may be for receiving andtransmitting network packet on a first network, and another networkstack for receiving and transmitting network packets on a secondnetwork. In one embodiment, the network stack 267 comprises a buffer 243for queuing one or more network packets for transmission by theappliance 200.

As shown in FIG. 2, the kernel space 204 includes the cache manager 232,a high-speed layer 2-7 integrated packet engine 240, an encryptionengine 234, a policy engine 236 and multi-protocol compression logic238. Running these components or processes 232, 240, 234, 236 and 238 inkernel space 204 or kernel mode instead of the user space 202 improvesthe performance of each of these components, alone and in combination.Kernel operation means that these components or processes 232, 240, 234,236 and 238 run in the core address space of the operating system of thedevice 200. For example, running the encryption engine 234 in kernelmode improves encryption performance by moving encryption and decryptionoperations to the kernel, thereby reducing the number of transitionsbetween the memory space or a kernel thread in kernel mode and thememory space or a thread in user mode. For example, data obtained inkernel mode may not need to be passed or copied to a process or threadrunning in user mode, such as from a kernel level data structure to auser level data structure. In another aspect, the number of contextswitches between kernel mode and user mode are also reduced.Additionally, synchronization of and communications between any of thecomponents or processes 232, 240, 235, 236 and 238 can be performed moreefficiently in the kernel space 204.

In some embodiments, any portion of the components 232, 240, 234, 236and 238 may run or operate in the kernel space 204, while other portionsof these components 232, 240, 234, 236 and 238 may run or operate inuser space 202. In one embodiment, the appliance 200 uses a kernel-leveldata structure providing access to any portion of one or more networkpackets, for example, a network packet comprising a request from aclient 102 or a response from a server 106. In some embodiments, thekernel-level data structure may be obtained by the packet engine 240 viaa transport layer driver interface or filter to the network stack 267.The kernel-level data structure may comprise any interface and/or dataaccessible via the kernel space 204 related to the network stack 267,network traffic or packets received or transmitted by the network stack267. In other embodiments, the kernel-level data structure may be usedby any of the components or processes 232, 240, 234, 236 and 238 toperform the desired operation of the component or process. In oneembodiment, a component 232, 240, 234, 236 and 238 is running in kernelmode 204 when using the kernel-level data structure, while in anotherembodiment, the component 232, 240, 234, 236 and 238 is running in usermode when using the kernel-level data structure. In some embodiments,the kernel-level data structure may be copied or passed to a secondkernel-level data structure, or any desired user-level data structure.

The cache manager 232 may comprise software, hardware or any combinationof software and hardware to provide cache access, control and managementof any type and form of content, such as objects or dynamicallygenerated objects served by the originating servers 106. The data,objects or content processed and stored by the cache manager 232 maycomprise data in any format, such as a markup language, or communicatedvia any protocol. In some embodiments, the cache manager 232 duplicatesoriginal data stored elsewhere or data previously computed, generated ortransmitted, in which the original data may require longer access timeto fetch, compute or otherwise obtain relative to reading a cache memoryelement. Once the data is stored in the cache memory element, future usecan be made by accessing the cached copy rather than refetching orrecomputing the original data, thereby reducing the access time. In someembodiments, the cache memory element may comprise a data object inmemory 264 of device 200. In other embodiments, the cache memory elementmay comprise memory having a faster access time than memory 264. Inanother embodiment, the cache memory element may comprise any type andform of storage element of the device 200, such as a portion of a harddisk. In some embodiments, the processing unit 262 may provide cachememory for use by the cache manager 232. In yet further embodiments, thecache manager 232 may use any portion and combination of memory,storage, or the processing unit for caching data, objects, and othercontent.

Furthermore, the cache manager 232 includes any logic, functions, rules,or operations to perform any embodiments of the techniques of theappliance 200 described herein. For example, the cache manager 232includes logic or functionality to invalidate objects based on theexpiration of an invalidation time period or upon receipt of aninvalidation command from a client 102 or server 106. In someembodiments, the cache manager 232 may operate as a program, service,process or task executing in the kernel space 204, and in otherembodiments, in the user space 202. In one embodiment, a first portionof the cache manager 232 executes in the user space 202 while a secondportion executes in the kernel space 204. In some embodiments, the cachemanager 232 can comprise any type of general purpose processor (GPP), orany other type of integrated circuit, such as a Field Programmable GateArray (FPGA), Programmable Logic Device (PLD), or Application SpecificIntegrated Circuit (ASIC).

The policy engine 236 may include, for example, an intelligentstatistical engine or other programmable application(s). In oneembodiment, the policy engine 236 provides a configuration mechanism toallow a user to identify, specify, define or configure a caching policy.Policy engine 236, in some embodiments, also has access to memory tosupport data structures such as lookup tables or hash tables to enableuser-selected caching policy decisions. In other embodiments, the policyengine 236 may comprise any logic, rules, functions or operations todetermine and provide access, control and management of objects, data orcontent being cached by the appliance 200 in addition to access, controland management of security, network traffic, network access, compressionor any other function or operation performed by the appliance 200.Further examples of specific caching policies are further describedherein.

The encryption engine 234 comprises any logic, business rules, functionsor operations for handling the processing of any security relatedprotocol, such as SSL or TLS, or any function related thereto. Forexample, the encryption engine 234 encrypts and decrypts networkpackets, or any portion thereof, communicated via the appliance 200. Theencryption engine 234 may also setup or establish SSL or TLS connectionson behalf of the client 102 a-102 n, server 106 a-106 n, or appliance200. As such, the encryption engine 234 provides offloading andacceleration of SSL processing. In one embodiment, the encryption engine234 uses a tunneling protocol to provide a virtual private networkbetween a client 102 a-102 n and a server 106 a-106 n. In someembodiments, the encryption engine 234 is in communication with theEncryption processor 260. In other embodiments, the encryption engine234 comprises executable instructions running on the Encryptionprocessor 260.

The multi-protocol compression engine 238 comprises any logic, businessrules, function or operations for compressing one or more protocols of anetwork packet, such as any of the protocols used by the network stack267 of the device 200. In one embodiment, multi-protocol compressionengine 238 compresses bi-directionally between clients 102 a-102 n andservers 106 a-106 n any TCP/IP based protocol, including MessagingApplication Programming Interface (MAPI) (email), File Transfer Protocol(FTP), HyperText Transfer Protocol (HTTP), Common Internet File System(CIFS) protocol (file transfer), Independent Computing Architecture(ICA) protocol, Remote Desktop Protocol (RDP), Wireless ApplicationProtocol (WAP), Mobile IP protocol, and Voice Over IP (VoIP) protocol.In other embodiments, multi-protocol compression engine 238 providescompression of Hypertext Markup Language (HTML) based protocols and insome embodiments, provides compression of any markup languages, such asthe Extensible Markup Language (XML). In one embodiment, themulti-protocol compression engine 238 provides compression of anyhigh-performance protocol, such as any protocol designed for appliance200 to appliance 200 communications. In another embodiment, themulti-protocol compression engine 238 compresses any payload of or anycommunication using a modified transport control protocol, such asTransaction TCP (T/TCP), TCP with selection acknowledgements (TCP-SACK),TCP with large windows (TCP-LW), a congestion prediction protocol suchas the TCP-Vegas protocol, and a TCP spoofing protocol.

As such, the multi-protocol compression engine 238 acceleratesperformance for users accessing applications via desktop clients, e.g.,Microsoft Outlook and non-Web thin clients, such as any client launchedby popular enterprise applications like Oracle, SAP and Siebel, and evenmobile clients, such as the Pocket PC. In some embodiments, themulti-protocol compression engine 238 by executing in the kernel mode204 and integrating with packet processing engine 240 accessing thenetwork stack 267 is able to compress any of the protocols carried bythe TCP/IP protocol, such as any application layer protocol.

High speed layer 2-7 integrated packet engine 240, also generallyreferred to as a packet processing engine or packet engine, isresponsible for managing the kernel-level processing of packets receivedand transmitted by appliance 200 via network ports 266. The high speedlayer 2-7 integrated packet engine 240 may comprise a buffer for queuingone or more network packets during processing, such as for receipt of anetwork packet or transmission of a network packet. Additionally, thehigh speed layer 2-7 integrated packet engine 240 is in communicationwith one or more network stacks 267 to send and receive network packetsvia network ports 266. The high speed layer 2-7 integrated packet engine240 works in conjunction with encryption engine 234, cache manager 232,policy engine 236 and multi-protocol compression logic 238. Inparticular, encryption engine 234 is configured to perform SSLprocessing of packets, policy engine 236 is configured to performfunctions related to traffic management such as request-level contentswitching and request-level cache redirection, and multi-protocolcompression logic 238 is configured to perform functions related tocompression and decompression of data.

The high speed layer 2-7 integrated packet engine 240 includes a packetprocessing timer 242. In one embodiment, the packet processing timer 242provides one or more time intervals to trigger the processing ofincoming, i.e., received, or outgoing, i.e., transmitted, networkpackets. In some embodiments, the high speed layer 2-7 integrated packetengine 240 processes network packets responsive to the timer 242. Thepacket processing timer 242 provides any type and form of signal to thepacket engine 240 to notify, trigger, or communicate a time relatedevent, interval or occurrence. In many embodiments, the packetprocessing timer 242 operates in the order of milliseconds, such as forexample 100 ms, 50 ms or 25 ms. For example, in some embodiments, thepacket processing timer 242 provides time intervals or otherwise causesa network packet to be processed by the high speed layer 2-7 integratedpacket engine 240 at a 10 ms time interval, while in other embodiments,at a 5 ms time interval, and still yet in further embodiments, as shortas a 3, 2, or 1 ms time interval. The high speed layer 2-7 integratedpacket engine 240 may be interfaced, integrated or in communication withthe encryption engine 234, cache manager 232, policy engine 236 andmulti-protocol compression engine 238 during operation. As such, any ofthe logic, functions, or operations of the encryption engine 234, cachemanager 232, policy engine 236 and multi-protocol compression logic 238may be performed responsive to the packet processing timer 242 and/orthe packet engine 240. Therefore, any of the logic, functions, oroperations of the encryption engine 234, cache manager 232, policyengine 236 and multi-protocol compression logic 238 may be performed atthe granularity of time intervals provided via the packet processingtimer 242, for example, at a time interval of less than or equal to 10ms. For example, in one embodiment, the cache manager 232 may performinvalidation of any cached objects responsive to the high speed layer2-7 integrated packet engine 240 and/or the packet processing timer 242.In another embodiment, the expiry or invalidation time of a cachedobject can be set to the same order of granularity as the time intervalof the packet processing timer 242, such as at every 10 ms.

In contrast to kernel space 204, user space 202 is the memory area orportion of the operating system used by user mode applications orprograms otherwise running in user mode. A user mode application may notaccess kernel space 204 directly and uses service calls in order toaccess kernel services. As shown in FIG. 2, user space 202 of appliance200 includes a graphical user interface (GUI) 210, a command lineinterface (CLI) 212, shell services 214, health monitoring program 216,and daemon services 218. GUI 210 and CLI 212 provide a means by which asystem administrator or other user can interact with and control theoperation of appliance 200, such as via the operating system of theappliance 200. The GUI 210 or CLI 212 can comprise code running in userspace 202 or kernel space 204. The GUI 210 may be any type and form ofgraphical user interface and may be presented via text, graphical orotherwise, by any type of program or application, such as a browser. TheCLI 212 may be any type and form of command line or text-basedinterface, such as a command line provided by the operating system. Forexample, the CLI 212 may comprise a shell, which is a tool to enableusers to interact with the operating system. In some embodiments, theCLI 212 may be provided via a bash, csh, tcsh, or ksh type shell. Theshell services 214 comprises the programs, services, tasks, processes orexecutable instructions to support interaction with the appliance 200 oroperating system by a user via the GUI 210 and/or CLI 212.

Health monitoring program 216 is used to monitor, check, report andensure that network systems are functioning properly and that users arereceiving requested content over a network. Health monitoring program216 comprises one or more programs, services, tasks, processes orexecutable instructions to provide logic, rules, functions or operationsfor monitoring any activity of the appliance 200. In some embodiments,the health monitoring program 216 intercepts and inspects any networktraffic passed via the appliance 200. In other embodiments, the healthmonitoring program 216 interfaces by any suitable means and/ormechanisms with one or more of the following: the encryption engine 234,cache manager 232, policy engine 236, multi-protocol compression logic238, packet engine 240, daemon services 218, and shell services 214. Assuch, the health monitoring program 216 may call any applicationprogramming interface (API) to determine a state, status, or health ofany portion of the appliance 200. For example, the health monitoringprogram 216 may ping or send a status inquiry on a periodic basis tocheck if a program, process, service or task is active and currentlyrunning. In another example, the health monitoring program 216 may checkany status, error or history logs provided by any program, process,service or task to determine any condition, status or error with anyportion of the appliance 200.

Daemon services 218 are programs that run continuously or in thebackground and handle periodic service requests received by appliance200. In some embodiments, a daemon service may forward the requests toother programs or processes, such as another daemon service 218 asappropriate. As known to those skilled in the art, a daemon service 218may run unattended to perform continuous or periodic system widefunctions, such as network control, or to perform any desired task. Insome embodiments, one or more daemon services 218 run in the user space202, while in other embodiments, one or more daemon services 218 run inthe kernel space.

Referring now to FIG. 2B, another embodiment of the appliance 200 isdepicted. In brief overview, the appliance 200 provides one or more ofthe following services, functionality or operations: SSL VPNconnectivity 280, switching/load balancing 284, Domain Name Serviceresolution 286, acceleration 288 and an application firewall 290 forcommunications between one or more clients 102 and one or more servers106. Each of the servers 106 may provide one or more network relatedservices 270 a-270 n (referred to as services 270). For example, aserver 106 may provide an http service 270. The appliance 200 comprisesone or more virtual servers or virtual internet protocol servers,referred to as a vServer, VIP server, or just VIP 275 a-275 n (alsoreferred herein as vServer 275). The vServer 275 receives, intercepts orotherwise processes communications between a client 102 and a server 106in accordance with the configuration and operations of the appliance200.

The vServer 275 may comprise software, hardware or any combination ofsoftware and hardware. The vServer 275 may comprise any type and form ofprogram, service, task, process or executable instructions operating inuser mode 202, kernel mode 204 or any combination thereof in theappliance 200. The vServer 275 includes any logic, functions, rules, oroperations to perform any embodiments of the techniques describedherein, such as SSL VPN 280, switching/load balancing 284, Domain NameService resolution 286, acceleration 288 and an application firewall290. In some embodiments, the vServer 275 establishes a connection to aservice 270 of a server 106. The service 275 may comprise any program,application, process, task or set of executable instructions capable ofconnecting to and communicating to the appliance 200, client 102 orvServer 275. For example, the service 275 may comprise a web server,http server, ftp, email or database server. In some embodiments, theservice 270 is a daemon process or network driver for listening,receiving and/or sending communications for an application, such asemail, database or an enterprise application. In some embodiments, theservice 270 may communicate on a specific IP address, or IP address andport.

In some embodiments, the vServer 275 applies one or more policies of thepolicy engine 236 to network communications between the client 102 andserver 106. In one embodiment, the policies are associated with aVServer 275. In another embodiment, the policies are based on a user, ora group of users. In yet another embodiment, a policy is global andapplies to one or more vServers 275 a-275 n, and any user or group ofusers communicating via the appliance 200. In some embodiments, thepolicies of the policy engine have conditions upon which the policy isapplied based on any content of the communication, such as internetprotocol address, port, protocol type, header or fields in a packet, orthe context of the communication, such as user, group of the user,vServer 275, transport layer connection, and/or identification orattributes of the client 102 or server 106.

In other embodiments, the appliance 200 communicates or interfaces withthe policy engine 236 to determine authentication and/or authorizationof a remote user or a remote client 102 to access the computingenvironment 15, application, and/or data file from a server 106. Inanother embodiment, the appliance 200 communicates or interfaces withthe policy engine 236 to determine authentication and/or authorizationof a remote user or a remote client 102 to have the application deliverysystem 190 deliver one or more of the computing environment 15,application, and/or data file. In yet another embodiment, the appliance200 establishes a VPN or SSL VPN connection based on the policy engine's236 authentication and/or authorization of a remote user or a remoteclient 102 In one embodiment, the appliance 200 controls the flow ofnetwork traffic and communication sessions based on policies of thepolicy engine 236. For example, the appliance 200 may control the accessto a computing environment 15, application or data file based on thepolicy engine 236.

In some embodiments, the vServer 275 establishes a transport layerconnection, such as a TCP or UDP connection with a client 102 via theclient agent 120. In one embodiment, the vServer 275 listens for andreceives communications from the client 102. In other embodiments, thevServer 275 establishes a transport layer connection, such as a TCP orUDP connection with a client server 106. In one embodiment, the vServer275 establishes the transport layer connection to an internet protocoladdress and port of a server 270 running on the server 106. In anotherembodiment, the vServer 275 associates a first transport layerconnection to a client 102 with a second transport layer connection tothe server 106. In some embodiments, a vServer 275 establishes a pool oftransport layer connections to a server 106 and multiplexes clientrequests via the pooled transport layer connections.

In some embodiments, the appliance 200 provides a SSL VPN connection 280between a client 102 and a server 106. For example, a client 102 on afirst network 102 requests to establish a connection to a server 106 ona second network 104′. In some embodiments, the second network 104′ isnot routable from the first network 104. In other embodiments, theclient 102 is on a public network 104 and the server 106 is on a privatenetwork 104′, such as a corporate network. In one embodiment, the clientagent 120 intercepts communications of the client 102 on the firstnetwork 104, encrypts the communications, and transmits thecommunications via a first transport layer connection to the appliance200. The appliance 200 associates the first transport layer connectionon the first network 104 to a second transport layer connection to theserver 106 on the second network 104. The appliance 200 receives theintercepted communication from the client agent 102, decrypts thecommunications, and transmits the communication to the server 106 on thesecond network 104 via the second transport layer connection. The secondtransport layer connection may be a pooled transport layer connection.As such, the appliance 200 provides an end-to-end secure transport layerconnection for the client 102 between the two networks 104, 104′.

In one embodiment, the appliance 200 hosts an intranet internet protocolor intranetIP 282 address of the client 102 on the virtual privatenetwork 104. The client 102 has a local network identifier, such as anInternet protocol (IP) address and/or host name on the first network104. When connected to the second network 104′ via the appliance 200,the appliance 200 establishes, assigns or otherwise provides anIntranetIP, which is network identifier, such as IP address and/or hostname, for the client 102 on the second network 104′. The appliance 200listens for and receives on the second or private network 104′ for anycommunications directed towards the client 102 using the client'sestablished IntranetIP 282. In one embodiment, the appliance 200 acts asor on behalf of the client 102 on the second private network 104. Forexample, in another embodiment, a vServer 275 listens for and respondsto communications to the IntranetIP 282 of the client 102. In someembodiments, if a computing device 100 on the second network 104′transmits a request, the appliance 200 processes the request as if itwere the client 102. For example, the appliance 200 may respond to aping to the client's IntranetIP 282. In another example, the appliancemay establish a connection, such as a TCP or UDP connection, withcomputing device 100 on the second network 104 requesting a connectionwith the client's IntranetIP 282.

In some embodiments, the appliance 200 provides one or more of thefollowing acceleration techniques 288 to communications between theclient 102 and server 106: 1) compression; 2) decompression; 3)Transmission Control Protocol pooling; 4) Transmission Control Protocolmultiplexing; 5) Transmission Control Protocol buffering; and 6)caching.

In one embodiment, the appliance 200 relieves servers 106 of much of theprocessing load caused by repeatedly opening and closing transportlayers connections to clients 102 by opening one or more transport layerconnections with each server 106 and maintaining these connections toallow repeated data accesses by clients via the Internet. This techniqueis referred to herein as “connection pooling”.

In some embodiments, in order to seamlessly splice communications from aclient 102 to a server 106 via a pooled transport layer connection, theappliance 200 translates or multiplexes communications by modifyingsequence number and acknowledgment numbers at the transport layerprotocol level. This is referred to as “connection multiplexing”. Insome embodiments, no application layer protocol interaction is required.For example, in the case of an in-bound packet (that is, a packetreceived from a client 102), the source network address of the packet ischanged to that of an output port of appliance 200, and the destinationnetwork address is changed to that of the intended server. In the caseof an outbound packet (that is, one received from a server 106), thesource network address is changed from that of the server 106 to that ofan output port of appliance 200 and the destination address is changedfrom that of appliance 200 to that of the requesting client 102. Thesequence numbers and acknowledgment numbers of the packet are alsotranslated to sequence numbers and acknowledgement expected by theclient 102 on the appliance's 200 transport layer connection to theclient 102. In some embodiments, the packet checksum of the transportlayer protocol is recalculated to account for these translations.

In another embodiment, the appliance 200 provides switching orload-balancing functionality 284 for communications between the client102 and server 106. In some embodiments, the appliance 200 distributestraffic and directs client requests to a server 106 based on layer 4 orapplication-layer request data. In one embodiment, although the networklayer or layer 2 of the network packet identifies a destination server106, the appliance 200 determines the server 106 to distribute thenetwork packet by application information and data carried as payload ofthe transport layer packet. In one embodiment, the health monitoringprograms 216 of the appliance 200 monitor the health of servers todetermine the server 106 for which to distribute a client's request. Insome embodiments, if the appliance 200 detects a server 106 is notavailable or has a load over a predetermined threshold, the appliance200 can direct or distribute client requests to another server 106.

In some embodiments, the appliance 200 acts as a Domain Name Service(DNS) resolver or otherwise provides resolution of a DNS request fromclients 102. In some embodiments, the appliance intercepts' a DNSrequest transmitted by the client 102. In one embodiment, the appliance200 responds to a client's DNS request with an IP address of or hostedby the appliance 200. In this embodiment, the client 102 transmitsnetwork communication for the domain name to the appliance 200. Inanother embodiment, the appliance 200 responds to a client's DNS requestwith an IP address of or hosted by a second appliance 200′. In someembodiments, the appliance 200 responds to a client's DNS request withan IP address of a server 106 determined by the appliance 200.

In yet another embodiment, the appliance 200 provides applicationfirewall functionality 290 for communications between the client 102 andserver 106. In one embodiment, the policy engine 236 provides rules fordetecting and blocking illegitimate requests. In some embodiments, theapplication firewall 290 protects against denial of service (DoS)attacks. In other embodiments, the appliance inspects the content ofintercepted requests to identify and block application-based attacks. Insome embodiments, the rules/policy engine 236 comprises one or moreapplication firewall or security control policies for providingprotections against various classes and types of web or Internet basedvulnerabilities, such as one or more of the following: 1) bufferoverflow, 2) CGI-BIN parameter manipulation, 3) form/hidden fieldmanipulation, 4) forceful browsing, 5) cookie or session poisoning, 6)broken access control list (ACLs) or weak passwords, 7) cross-sitescripting (XSS), 8) command injection, 9) SQL injection, 10) errortriggering sensitive information leak, 11) insecure use of cryptography,12) server misconfiguration, 13) back doors and debug options, 14)website defacement, 15) platform or operating systems vulnerabilities,and 16) zero-day exploits. In an embodiment, the application firewall290 provides HTML form field protection in the form of inspecting oranalyzing the network communication for one or more of the following: 1)required fields are returned, 2) no added field allowed, 3) read-onlyand hidden field enforcement, 4) drop-down list and radio button fieldconformance, and 5) form-field max-length enforcement. In someembodiments, the application firewall 290 ensures cookies are notmodified. In other embodiments, the application firewall 290 protectsagainst forceful browsing by enforcing legal URLs.

In still yet other embodiments, the application firewall 290 protectsany confidential information contained in the network communication. Theapplication firewall 290 may inspect or analyze any networkcommunication in accordance with the rules or polices of the engine 236to identify any confidential information in any field of the networkpacket. In some embodiments, the application firewall 290 identifies inthe network communication one or more occurrences of a credit cardnumber, password, social security number, name, patient code, contactinformation, and age. The encoded portion of the network communicationmay comprise these occurrences or the confidential information. Based onthese occurrences, in one embodiment, the application firewall 290 maytake a policy action on the network communication, such as preventtransmission of the network communication. In another embodiment, theapplication firewall 290 may rewrite, remove or otherwise mask suchidentified occurrence or confidential information.

Still referring to FIG. 2B, the appliance 200 may include a performancemonitoring agent 197 as discussed above in conjunction with FIG. 1D. Inone embodiment, the appliance 200 receives the monitoring agent 197 fromthe monitoring service 198 or monitoring server 106 as depicted in FIG.1D. In some embodiments, the appliance 200 stores the monitoring agent197 in storage, such as disk, for delivery to any client or server incommunication with the appliance 200. For example, in one embodiment,the appliance 200 transmits the monitoring agent 197 to a client uponreceiving a request to establish a transport layer connection. In otherembodiments, the appliance 200 transmits the monitoring agent 197 uponestablishing the transport layer connection with the client 102. Inanother embodiment, the appliance 200 transmits the monitoring agent 197to the client upon intercepting or detecting a request for a web page.In yet another embodiment, the appliance 200 transmits the monitoringagent 197 to a client or a server in response to a request from themonitoring server 198. In one embodiment, the appliance 200 transmitsthe monitoring agent 197 to a second appliance 200′ or appliance 205.

In other embodiments, the appliance 200 executes the monitoring agent197. In one embodiment, the monitoring agent 197 measures and monitorsthe performance of any application, program, process, service, task orthread executing on the appliance 200. For example, the monitoring agent197 may monitor and measure performance and operation of vServers275A-275N. In another embodiment, the monitoring agent 197 measures andmonitors the performance of any transport layer connections of theappliance 200. In some embodiments, the monitoring agent 197 measuresand monitors the performance of any user sessions traversing theappliance 200. In one embodiment, the monitoring agent 197 measures andmonitors the performance of any virtual private network connectionsand/or sessions traversing the appliance 200, such an SSL VPN session.In still further embodiments, the monitoring agent 197 measures andmonitors the memory, CPU and disk usage and performance of the appliance200. In yet another embodiment, the monitoring agent 197 measures andmonitors the performance of any acceleration technique 288 performed bythe appliance 200, such as SSL offloading, connection pooling andmultiplexing, caching, and compression. In some embodiments, themonitoring agent 197 measures and monitors the performance of any loadbalancing and/or content switching 284 performed by the appliance 200.In other embodiments, the monitoring agent 197 measures and monitors theperformance of application firewall 290 protection and processingperformed by the appliance 200.

C. Client Agent

Referring now to FIG. 3, an embodiment of the client agent 120 isdepicted. The client 102 includes a client agent 120 for establishingand exchanging communications with the appliance 200 and/or server 106via a network 104. In brief overview, the client 102 operates oncomputing device 100 having an operating system with a kernel mode 302and a user mode 303, and a network stack 310 with one or more layers 310a-310 b. The client 102 may have installed and/or execute one or moreapplications. In some embodiments, one or more applications maycommunicate via the network stack 310 to a network 104. One of theapplications, such as a web browser, may also include a first program322. For example, the first program 322 may be used in some embodimentsto install and/or execute the client agent 120, or any portion thereof.The client agent 120 includes an interception mechanism, or interceptor350, for intercepting network communications from the network stack 310from the one or more applications.

The network stack 310 of the client 102 may comprise any type and formof software, or hardware, or any combinations thereof, for providingconnectivity to and communications with a network. In one embodiment,the network stack 310 comprises a software implementation for a networkprotocol suite. The network stack 310 may comprise one or more networklayers, such as any networks layers of the Open Systems Interconnection(OSI) communications model as those skilled in the art recognize andappreciate. As such, the network stack 310 may comprise any type andform of protocols for any of the following layers of the OSI model: 1)physical link layer, 2) data link layer, 3) network layer, 4) transportlayer, 5) session layer, 6) presentation layer, and 7) applicationlayer. In one embodiment, the network stack 310 may comprise a transportcontrol protocol (TCP) over the network layer protocol of the internetprotocol (IP), generally referred to as TCP/IP. In some embodiments, theTCP/IP protocol may be carried over the Ethernet protocol, which maycomprise any of the family of IEEE wide-area-network (WAN) orlocal-area-network (LAN) protocols, such as those protocols covered bythe IEEE 802.3. In some embodiments, the network stack 310 comprises anytype and form of a wireless protocol, such as IEEE 802.11 and/or mobileinternet protocol.

In view of a TCP/IP based network, any TCP/IP based protocol may beused, including Messaging Application Programming Interface (MAPI)(email), File Transfer Protocol (FTP), HyperText Transfer Protocol(HTTP), Common Internet File System (CIFS) protocol (file transfer),Independent Computing Architecture (ICA) protocol, Remote DesktopProtocol (RDP), Wireless Application Protocol (WAP), Mobile IP protocol,and Voice Over IP (VoIP) protocol. In another embodiment, the networkstack 310 comprises any type and form of transport control protocol,such as a modified transport control protocol, for example a TransactionTCP (T/TCP), TCP with selection acknowledgements (TCP-SACK), TCP withlarge windows (TCP-LW), a congestion prediction protocol such as theTCP-Vegas protocol, and a TCP spoofing protocol. In other embodiments,any type and form of user datagram protocol (UDP), such as UDP over IP,may be used by the network stack 310, such as for voice communicationsor real-time data communications.

Furthermore, the network stack 310 may include one or more networkdrivers supporting the one or more layers, such as a TCP driver or anetwork layer driver. The network drivers may be included as part of theoperating system of the computing device 100 or as part of any networkinterface cards or other network access components of the computingdevice 100. In some embodiments, any of the network drivers of thenetwork stack 310 may be customized, modified or adapted to provide acustom or modified portion of the network stack 310 in support of any ofthe techniques described herein. In other embodiments, the accelerationprogram 120 is designed and constructed to operate with or work inconjunction with the network stack 310 installed or otherwise providedby the operating system of the client 102.

The network stack 310 comprises any type and form of interfaces forreceiving, obtaining, providing or otherwise accessing any informationand data related to network communications of the client 102. In oneembodiment, an interface to the network stack 310 comprises anapplication programming interface (API). The interface may also compriseany function call, hooking or filtering mechanism, event or call backmechanism, or any type of interfacing technique. The network stack 310via the interface may receive or provide any type and form of datastructure, such as an object, related to functionality or operation ofthe network stack 310. For example, the data structure may compriseinformation and data related to a network packet or one or more networkpackets. In some embodiments, the data structure comprises a portion ofthe network packet processed at a protocol layer of the network stack310, such as a network packet of the transport layer. In someembodiments, the data structure 325 comprises a kernel-level datastructure, while in other embodiments, the data structure 325 comprisesa user-mode data structure. A kernel-level data structure may comprise adata structure obtained or related to a portion of the network stack 310operating in kernel-mode 302, or a network driver or other softwarerunning in kernel-mode 302, or any data structure obtained or receivedby a service, process, task, thread or other executable instructionsrunning or operating in kernel-mode of the operating system.

Additionally, some portions of the network stack 310 may execute oroperate in kernel-mode 302, for example, the data link or network layer,while other portions execute or operate in user-mode 303, such as anapplication layer of the network stack 310. For example, a first portion310 a of the network stack may provide user-mode access to the networkstack 310 to an application while a second portion 310 a of the networkstack 310 provides access to a network. In some embodiments, a firstportion 310 a of the network stack may comprise one or more upper layersof the network stack 310, such as any of layers 5-7. In otherembodiments, a second portion 310 b of the network stack 310 comprisesone or more lower layers, such as any of layers 1-4. Each of the firstportion 310 a and second portion 310 b of the network stack 310 maycomprise any portion of the network stack 310, at any one or morenetwork layers, in user-mode 203, kernel-mode, 202, or combinationsthereof, or at any portion of a network layer or interface point to anetwork layer or any portion of or interface point to the user-mode 203and kernel-mode 203.

The interceptor 350 may comprise software, hardware, or any combinationof software and hardware. In one embodiment, the interceptor 350intercept a network communication at any point in the network stack 310,and redirects or transmits the network communication to a destinationdesired, managed or controlled by the interceptor 350 or client agent120. For example, the interceptor 350 may intercept a networkcommunication of a network stack 310 of a first network and transmit thenetwork communication to the appliance 200 for transmission on a secondnetwork 104. In some embodiments, the interceptor 350 comprises any typeinterceptor 350 comprises a driver, such as a network driver constructedand designed to interface and work with the network stack 310. In someembodiments, the client agent 120 and/or interceptor 350 operates at oneor more layers of the network stack 310, such as at the transport layer.In one embodiment, the interceptor 350 comprises a filter driver,hooking mechanism, or any form and type of suitable network driverinterface that interfaces to the transport layer of the network stack,such as via the transport driver interface (TDI). In some embodiments,the interceptor 350 interfaces to a first protocol layer, such as thetransport layer and another protocol layer, such as any layer above thetransport protocol layer, for example, an application protocol layer. Inone embodiment, the interceptor 350 may comprise a driver complying withthe Network Driver Interface Specification (NDIS), or a NDIS driver. Inanother embodiment, the interceptor 350 may comprise a min-filter or amini-port driver. In one embodiment, the interceptor 350, or portionthereof, operates in kernel-mode 202. In another embodiment, theinterceptor 350, or portion thereof, operates in user-mode 203. In someembodiments, a portion of the interceptor 350 operates in kernel-mode202 while another portion of the interceptor 350 operates in user-mode203. In other embodiments, the client agent 120 operates in user-mode203 but interfaces via the interceptor 350 to a kernel-mode driver,process, service, task or portion of the operating system, such as toobtain a kernel-level data structure 225. In further embodiments, theinterceptor 350 is a user-mode application or program, such asapplication.

In one embodiment, the interceptor 350 intercepts any transport layerconnection requests. In these embodiments, the interceptor 350 executetransport layer application programming interface (API) calls to set thedestination information, such as destination IP address and/or port to adesired location for the location. In this manner, the interceptor 350intercepts and redirects the transport layer connection to a IP addressand port controlled or managed by the interceptor 350 or client agent120. In one embodiment, the interceptor 350 sets the destinationinformation for the connection to a local IP address and port of theclient 102 on which the client agent 120 is listening. For example, theclient agent 120 may comprise a proxy service listening on a local IPaddress and port for redirected transport layer communications. In someembodiments, the client agent 120 then communicates the redirectedtransport layer communication to the appliance 200.

In some embodiments, the interceptor 350 intercepts a Domain NameService (DNS) request. In one embodiment, the client agent 120 and/orinterceptor 350 resolves the DNS request. In another embodiment, theinterceptor transmits the intercepted DNS request to the appliance 200for DNS resolution. In one embodiment, the appliance 200 resolves theDNS request and communicates the DNS response to the client agent 120.In some embodiments, the appliance 200 resolves the DNS request viaanother appliance 200′ or a DNS server 106.

In yet another embodiment, the client agent 120 may comprise two agents120 and 120′. In one embodiment, a first agent 120 may comprise aninterceptor 350 operating at the network layer of the network stack 310.In some embodiments, the first agent 120 intercepts network layerrequests such as Internet Control Message Protocol (ICMP) requests(e.g., ping and traceroute). In other embodiments, the second agent 120′may operate at the transport layer and intercept transport layercommunications. In some embodiments, the first agent 120 interceptscommunications at one layer of the network stack 210 and interfaces withor communicates the intercepted communication to the second agent 120′.

The client agent 120 and/or interceptor 350 may operate at or interfacewith a protocol layer in a manner transparent to any other protocollayer of the network stack 310. For example, in one embodiment, theinterceptor 350 operates or interfaces with the transport layer of thenetwork stack 310 transparently to any protocol layer below thetransport layer, such as the network layer, and any protocol layer abovethe transport layer, such as the session, presentation or applicationlayer protocols. This allows the other protocol layers of the networkstack 310 to operate as desired and without modification for using theinterceptor 350. As such, the client agent 120 and/or interceptor 350can interface with the transport layer to secure, optimize, accelerate,route or load-balance any communications provided via any protocolcarried by the transport layer, such as any application layer protocolover TCP/IP.

Furthermore, the client agent 120 and/or interceptor may operate at orinterface with the network stack 310 in a manner transparent to anyapplication, a user of the client 102, and any other computing device,such as a server, in communications with the client 102. The clientagent 120 and/or interceptor 350 may be installed and/or executed on theclient 102 in a manner without modification of an application. In someembodiments, the user of the client 102 or a computing device incommunications with the client 102 are not aware of the existence,execution or operation of the client agent 120 and/or interceptor 350.As such, in some embodiments, the client agent 120 and/or interceptor350 is installed, executed, and/or operated transparently to anapplication, user of the client 102, another computing device, such as aserver, or any of the protocol layers above and/or below the protocollayer interfaced to by the interceptor 350.

The client agent 120 includes an acceleration program 302, a streamingclient 306, a collection agent 304, and/or monitoring agent 197. In oneembodiment, the client agent 120 comprises an Independent ComputingArchitecture (ICA) client, or any portion thereof, developed by CitrixSystems, Inc. of Fort Lauderdale, Fla., and is also referred to as anICA client. In some embodiments, the client 120 comprises an applicationstreaming client 306 for streaming an application from a server 106 to aclient 102. In some embodiments, the client agent 120 comprises anacceleration program 302 for accelerating communications between client102 and server 106. In another embodiment, the client agent 120 includesa collection agent 304 for performing end-point detection/scanning andcollecting end-point information for the appliance 200 and/or server106.

In some embodiments, the acceleration program 302 comprises aclient-side acceleration program for performing one or more accelerationtechniques to accelerate, enhance or otherwise improve a client'scommunications with and/or access to a server 106, such as accessing anapplication provided by a server 106. The logic, functions, and/oroperations of the executable instructions of the acceleration program302 may perform one or more of the following acceleration techniques: 1)multi-protocol compression, 2) transport control protocol pooling, 3)transport control protocol multiplexing, 4) transport control protocolbuffering, and 5) caching via a cache manager. Additionally, theacceleration program 302 may perform encryption and/or decryption of anycommunications received and/or transmitted by the client 102. In someembodiments, the acceleration program 302 performs one or more of theacceleration techniques in an integrated manner or fashion.Additionally, the acceleration program 302 can perform compression onany of the protocols, or multiple-protocols, carried as a payload of anetwork packet of the transport layer protocol.

The streaming client 306 comprises an application, program, process,service, task or executable instructions for receiving and executing astreamed application from a server 106. A server 106 may stream one ormore application data files to the streaming client 306 for playing,executing or otherwise causing to be executed the application on theclient 102. In some embodiments, the server 106 transmits a set ofcompressed or packaged application data files to the streaming client306. In some embodiments, the plurality of application files arecompressed and stored on a file server within an archive file such as aCAB, ZIP, SIT, TAR, JAR or other archive. In one embodiment, the server106 decompresses, unpackages or unarchives the application files andtransmits the files to the client 102. In another embodiment, the client102 decompresses, unpackages or unarchives the application files. Thestreaming client 306 dynamically installs the application, or portionthereof, and executes the application. In one embodiment, the streamingclient 306 may be an executable program. In some embodiments, thestreaming client 306 may be able to launch another executable program.

The collection agent 304 comprises an application, program, process,service, task or executable instructions for identifying, obtainingand/or collecting information about the client 102. In some embodiments,the appliance 200 transmits the collection agent 304 to the client 102or client agent 120. The collection agent 304 may be configuredaccording to one or more policies of the policy engine 236 of theappliance. In other embodiments, the collection agent 304 transmitscollected information on the client 102 to the appliance 200. In oneembodiment, the policy engine 236 of the appliance 200 uses thecollected information to determine and provide access, authenticationand authorization control of the client's connection to a network 104.

In one embodiment, the collection agent 304 comprises an end-pointdetection and scanning mechanism, which identifies and determines one ormore attributes or characteristics of the client. For example, thecollection agent 304 may identify and determine any one or more of thefollowing client-side attributes: 1) the operating system an/or aversion of an operating system, 2) a service pack of the operatingsystem, 3) a running service, 4) a running process, and 5) a file. Thecollection agent 304 may also identify and determine the presence orversions of any one or more of the following on the client: 1) antivirussoftware, 2) personal firewall software, 3) anti-spam software, and 4)internet security software. The policy engine 236 may have one or morepolicies based on any one or more of the attributes or characteristicsof the client or client-side attributes.

In some embodiments, the client agent 120 includes a monitoring agent197 as discussed in conjunction with FIGS. 1D and 2B. The monitoringagent 197 may be any type and form of script, such as Visual Basic orJava script. In one embodiment, the monitoring agent 129 monitors andmeasures performance of any portion of the client agent 120. Forexample, in some embodiments, the monitoring agent 129 monitors andmeasures performance of the acceleration program 302. In anotherembodiment, the monitoring agent 129 monitors and measures performanceof the streaming client 306. In other embodiments, the monitoring agent129 monitors and measures performance of the collection agent 304. Instill another embodiment, the monitoring agent 129 monitors and measuresperformance of the interceptor 350. In some embodiments, the monitoringagent 129 monitors and measures any resource of the client 102, such asmemory, CPU and disk.

The monitoring agent 197 may monitor and measure performance of anyapplication of the client. In one embodiment, the monitoring agent 129monitors and measures performance of a browser on the client 102. Insome embodiments, the monitoring agent 197 monitors and measuresperformance of any application delivered via the client agent 120. Inother embodiments, the monitoring agent 197 measures and monitors enduser response times for an application, such as web-based or HTTPresponse times. The monitoring agent 197 may monitor and measureperformance of an ICA or RDP client. In another embodiment, themonitoring agent 197 measures and monitors metrics for a user session orapplication session. In some embodiments, monitoring agent 197 measuresand monitors an ICA or RDP session. In one embodiment, the monitoringagent 197 measures and monitors the performance of the appliance 200 inaccelerating delivery of an application and/or data to the client 102.

In some embodiments and still referring to FIG. 3, a first program 322may be used to install and/or execute the client agent 120, or portionthereof, such as the interceptor 350, automatically, silently,transparently, or otherwise. In one embodiment, the first program 322comprises a plugin component, such an ActiveX control or Java control orscript that is loaded into and executed by an application. For example,the first program comprises an ActiveX control loaded and run by a webbrowser application, such as in the memory space or context of theapplication. In another embodiment, the first program 322 comprises aset of executable instructions loaded into and run by the application,such as a browser. In one embodiment, the first program 322 comprises adesigned and constructed program to install the client agent 120. Insome embodiments, the first program 322 obtains, downloads, or receivesthe client agent 120 via the network from another computing device. Inanother embodiment, the first program 322 is an installer program or aplug and play manager for installing programs, such as network drivers,on the operating system of the client 102.

D. Systems and Methods for Providing Virtualized Application DeliveryController

Referring now to FIG. 4A, a block diagram depicts one embodiment of avirtualization environment 400. In brief overview, a computing device100 includes a hypervisor layer, a virtualization layer, and a hardwarelayer. The hypervisor layer includes a hypervisor 401 (also referred toas a virtualization manager) that allocates and manages access to anumber of physical resources in the hardware layer (e.g., theprocessor(s) 421, and disk(s) 428) by at least one virtual machineexecuting in the virtualization layer. The virtualization layer includesat least one operating system 410 and a plurality of virtual resourcesallocated to the at least one operating system 410. Virtual resourcesmay include, without limitation, a plurality of virtual processors 432a, 432 b, 432 c (generally 432), and virtual disks 442 a, 442 b, 442 c(generally 442), as well as virtual resources such as virtual memory andvirtual network interfaces. The plurality of virtual resources and theoperating system 410 may be referred to as a virtual machine 406. Avirtual machine 406 may include a control operating system 405 incommunication with the hypervisor 401 and used to execute applicationsfor managing and configuring other virtual machines on the computingdevice 100.

In greater detail, a hypervisor 401 may provide virtual resources to anoperating system in any manner which simulates the operating systemhaving access to a physical device. A hypervisor 401 may provide virtualresources to any number of guest operating systems 410 a, 410 b(generally 410). In some embodiments, a computing device 100 executesone or more types of hypervisors. In these embodiments, hypervisors maybe used to emulate virtual hardware, partition physical hardware,virtualize physical hardware, and execute virtual machines that provideaccess to computing environments. Hypervisors may include thosemanufactured by VMWare, Inc., of Palo Alto, Calif.; the XEN hypervisor,an open source product whose development is overseen by the open sourceXen.org community; HyperV, VirtualServer or virtual PC hypervisorsprovided by Microsoft, or others. In some embodiments, a computingdevice 100 executing a hypervisor that creates a virtual machineplatform on which guest operating systems may execute is referred to asa host server. In one of these embodiments, for example, the computingdevice 100 is a XEN SERVER provided by Citrix Systems, Inc., of FortLauderdale, Fla.

In some embodiments, a hypervisor 401 executes within an operatingsystem executing on a computing device. In one of these embodiments, acomputing device executing an operating system and a hypervisor 401 maybe said to have a host operating system (the operating system executingon the computing device), and a guest operating system (an operatingsystem executing within a computing resource partition provided by thehypervisor 401). In other embodiments, a hypervisor 401 interactsdirectly with hardware on a computing device, instead of executing on ahost operating system. In one of these embodiments, the hypervisor 401may be said to be executing on “bare metal,” referring to the hardwarecomprising the computing device.

In some embodiments, a hypervisor 401 may create a virtual machine 406a-c (generally 406) in which an operating system 410 executes. In one ofthese embodiments, for example, the hypervisor 401 loads a virtualmachine image to create a virtual machine 406. In another of theseembodiments, the hypervisor 401 executes an operating system 410 withinthe virtual machine 406. In still another of these embodiments, thevirtual machine 406 executes an operating system 410.

In some embodiments, the hypervisor 401 controls processor schedulingand memory partitioning for a virtual machine 406 executing on thecomputing device 100. In one of these embodiments, the hypervisor 401controls the execution of at least one virtual machine 406. In anotherof these embodiments, the hypervisor 401 presents at least one virtualmachine 406 with an abstraction of at least one hardware resourceprovided by the computing device 100. In other embodiments, thehypervisor 401 controls whether and how physical processor capabilitiesare presented to the virtual machine 406.

A control operating system 405 may execute at least one application formanaging and configuring the guest operating systems. In one embodiment,the control operating system 405 may execute an administrativeapplication, such as an application including a user interface providingadministrators with access to functionality for managing the executionof a virtual machine, including functionality for executing a virtualmachine, terminating an execution of a virtual machine, or identifying atype of physical resource for allocation to the virtual machine. Inanother embodiment, the hypervisor 401 executes the control operatingsystem 405 within a virtual machine 406 created by the hypervisor 401.In still another embodiment, the control operating system 405 executesin a virtual machine 406 that is authorized to directly access physicalresources on the computing device 100. In some embodiments, a controloperating system 405 a on a computing device 100 a may exchange datawith a control operating system 405 b on a computing device 100 b, viacommunications between a hypervisor 401 a and a hypervisor 401 b. Inthis way, one or more computing devices 100 may exchange data with oneor more of the other computing devices 100 regarding processors andother physical resources available in a pool of resources. In one ofthese embodiments, this functionality allows a hypervisor to manage apool of resources distributed across a plurality of physical computingdevices. In another of these embodiments, multiple hypervisors manageone or more of the guest operating systems executed on one of thecomputing devices 100.

In one embodiment, the control operating system 405 executes in avirtual machine 406 that is authorized to interact with at least oneguest operating system 410. In another embodiment, a guest operatingsystem 410 communicates with the control operating system 405 via thehypervisor 401 in order to request access to a disk or a network. Instill another embodiment, the guest operating system 410 and the controloperating system 405 may communicate via a communication channelestablished by the hypervisor 401, such as, for example, via a pluralityof shared memory pages made available by the hypervisor 401.

In some embodiments, the control operating system 405 includes a networkback-end driver for communicating directly with networking hardwareprovided by the computing device 100. In one of these embodiments, thenetwork back-end driver processes at least one virtual machine requestfrom at least one guest operating system 110. In other embodiments, thecontrol operating system 405 includes a block back-end driver forcommunicating with a storage element on the computing device 100. In oneof these embodiments, the block back-end driver reads and writes datafrom the storage element based upon at least one request received from aguest operating system 410.

In one embodiment, the control operating system 405 includes a toolsstack 404. In another embodiment, a tools stack 404 providesfunctionality for interacting with the hypervisor 401, communicatingwith other control operating systems 405 (for example, on a secondcomputing device 100 b), or managing virtual machines 406 b, 406 c onthe computing device 100. In another embodiment, the tools stack 404includes customized applications for providing improved managementfunctionality to an administrator of a virtual machine farm. In someembodiments, at least one of the tools stack 404 and the controloperating system 405 include a management API that provides an interfacefor remotely configuring and controlling virtual machines 406 running ona computing device 100. In other embodiments, the control operatingsystem 405 communicates with the hypervisor 401 through the tools stack104.

In one embodiment, the hypervisor 401 executes a guest operating system410 within a virtual machine 406 created by the hypervisor 401. Inanother embodiment, the guest operating system 410 provides a user ofthe computing device 100 with access to resources within a computingenvironment. In still another embodiment, a resource includes a program,an application, a document, a file, a plurality of applications, aplurality of files, an executable program file, a desktop environment, acomputing environment, or other resource made available to a user of thecomputing device 100. In yet another embodiment, the resource may bedelivered to the computing device 100 via a plurality of access methodsincluding, but not limited to, conventional installation directly on thecomputing device 100, delivery to the computing device 100 via a methodfor application streaming, delivery to the computing device 100 ofoutput data generated by an execution of the resource on a secondcomputing device 100′ and communicated to the computing device 100 via apresentation layer protocol, delivery to the computing device 100 ofoutput data generated by an execution of the resource via a virtualmachine executing on a second computing device 100′, or execution from aremovable storage device connected to the computing device 100, such asa USB device, or via a virtual machine executing on the computing device100 and generating output data. In some embodiments, the computingdevice 100 transmits output data generated by the execution of theresource to another computing device 100′.

In one embodiment, the guest operating system 410, in conjunction withthe virtual machine on which it executes, forms a fully-virtualizedvirtual machine which is not aware that it is a virtual machine; such amachine may be referred to as a “Domain U HVM (Hardware Virtual Machine)virtual machine”. In another embodiment, a fully-virtualized machineincludes software emulating a Basic Input/Output System (BIOS) in orderto execute an operating system within the fully-virtualized machine. Instill another embodiment, a fully-virtualized machine may include adriver that provides functionality by communicating with the hypervisor401. In such an embodiment, the driver may be aware that it executeswithin a virtualized environment. In another embodiment, the guestoperating system 410, in conjunction with the virtual machine on whichit executes, forms a paravirtualized virtual machine, which is awarethat it is a virtual machine; such a machine may be referred to as a“Domain U PV virtual machine”. In another embodiment, a paravirtualizedmachine includes additional drivers that a fully-virtualized machinedoes not include. In still another embodiment, the paravirtualizedmachine includes the network back-end driver and the block back-enddriver included in a control operating system 405, as described above.

Referring now to FIG. 4B, a block diagram depicts one embodiment of aplurality of networked computing devices in a system in which at leastone physical host executes a virtual machine. In brief overview, thesystem includes a management component 404 and a hypervisor 401. Thesystem includes a plurality of computing devices 100, a plurality ofvirtual machines 406, a plurality of hypervisors 401, a plurality ofmanagement components referred to as tools stacks 404, and a physicalresource 421, 428. The plurality of physical machines 100 may each beprovided as computing devices 100, described above in connection withFIGS. 1E-1H and 4A.

In greater detail, a physical disk 428 is provided by a computing device100 and stores at least a portion of a virtual disk 442. In someembodiments, a virtual disk 442 is associated with a plurality ofphysical disks 428. In one of these embodiments, one or more computingdevices 100 may exchange data with one or more of the other computingdevices 100 regarding processors and other physical resources availablein a pool of resources, allowing a hypervisor to manage a pool ofresources distributed across a plurality of physical computing devices.In some embodiments, a computing device 100 on which a virtual machine406 executes is referred to as a physical host 100 or as a host machine100.

The hypervisor executes on a processor on the computing device 100. Thehypervisor allocates, to a virtual disk, an amount of access to thephysical disk. In one embodiment, the hypervisor 401 allocates an amountof space on the physical disk. In another embodiment, the hypervisor 401allocates a plurality of pages on the physical disk. In someembodiments, the hypervisor provisions the virtual disk 442 as part of aprocess of initializing and executing a virtual machine 450.

In one embodiment, the management component 404 a is referred to as apool management component 404 a. In another embodiment, a managementoperating system 405 a, which may be referred to as a control operatingsystem 405 a, includes the management component. In some embodiments,the management component is referred to as a tools stack. In one ofthese embodiments, the management component is the tools stack 404described above in connection with FIG. 4A. In other embodiments, themanagement component 404 provides a user interface for receiving, from auser such as an administrator, an identification of a virtual machine406 to provision and/or execute. In still other embodiments, themanagement component 404 provides a user interface for receiving, from auser such as an administrator, the request for migration of a virtualmachine 406 b from one physical machine 100 to another. In furtherembodiments, the management component 404 a identifies a computingdevice 100 b on which to execute a requested virtual machine 406 d andinstructs the hypervisor 401 b on the identified computing device 100 bto execute the identified virtual machine; such a management componentmay be referred to as a pool management component.

Referring now to FIG. 4C, embodiments of a virtual application deliverycontroller or virtual appliance 450 are depicted. In brief overview, anyof the functionality and/or embodiments of the appliance 200 (e.g., anapplication delivery controller) described above in connection withFIGS. 2A and 2B may be deployed in any embodiment of the virtualizedenvironment described above in connection with FIGS. 4A and 4B. Insteadof the functionality of the application delivery controller beingdeployed in the form of an appliance 200, such functionality may bedeployed in a virtualized environment 400 on any computing device 100,such as a client 102, server 106 or appliance 200.

Referring now to FIG. 4C, a diagram of an embodiment of a virtualappliance 450 operating on a hypervisor 401 of a server 106 is depicted.As with the appliance 200 of FIGS. 2A and 2B, the virtual appliance 450may provide functionality for availability, performance, offload andsecurity. For availability, the virtual appliance may perform loadbalancing between layers 4 and 7 of the network and may also performintelligent service health monitoring. For performance increases vianetwork traffic acceleration, the virtual appliance may perform cachingand compression. To offload processing of any servers, the virtualappliance may perform connection multiplexing and pooling and/or SSLprocessing. For security, the virtual appliance may perform any of theapplication firewall functionality and SSL VPN function of appliance200.

Any of the modules of the appliance 200 as described in connection withFIG. 2A may be packaged, combined, designed or constructed in a form ofthe virtualized appliance delivery controller 450 deployable as one ormore software modules or components executable in a virtualizedenvironment 300 or non-virtualized environment on any server, such as anoff the shelf server. For example, the virtual appliance may be providedin the form of an installation package to install on a computing device.With reference to FIG. 2A, any of the cache manager 232, policy engine236, compression 238, encryption engine 234, packet engine 240, GUI 210,CLI 212, shell services 214 and health monitoring programs 216 may bedesigned and constructed as a software component or module to run on anyoperating system of a computing device and/or of a virtualizedenvironment 300. Instead of using the encryption processor 260,processor 262, memory 264 and network stack 267 of the appliance 200,the virtualized appliance 400 may use any of these resources as providedby the virtualized environment 400 or as otherwise available on theserver 106.

Still referring to FIG. 4C, and in brief overview, any one or morevServers 275A-275N may be in operation or executed in a virtualizedenvironment 400 of any type of computing device 100, such as any server106. Any of the modules or functionality of the appliance 200 describedin connection with FIG. 2B may be designed and constructed to operate ineither a virtualized or non-virtualized environment of a server. Any ofthe vServer 275, SSL VPN 280, Intranet UP 282, Switching 284, DNS 286,acceleration 288, App FW 280 and monitoring agent may be packaged,combined, designed or constructed in a form of application deliverycontroller 450 deployable as one or more software modules or componentsexecutable on a device and/or virtualized environment 400.

In some embodiments, a server may execute multiple virtual machines 406a-406 n in the virtualization environment with each virtual machinerunning the same or different embodiments of the virtual applicationdelivery controller 450. In some embodiments, the server may execute oneor more virtual appliances 450 on one or more virtual machines on a coreof a multi-core processing system. In some embodiments, the server mayexecute one or more virtual appliances 450 on one or more virtualmachines on each processor of a multiple processor device.

E. Systems and Methods for Providing a Multi-Core Architecture

In accordance with Moore's Law, the number of transistors that may beplaced on an integrated circuit may double approximately every twoyears. However, CPU speed increases may reach plateaus, for example CPUspeed has been around 3.5-4 GHz range since 2005. In some cases, CPUmanufacturers may not rely on CPU speed increases to gain additionalperformance. Some CPU manufacturers may add additional cores to theirprocessors to provide additional performance. Products, such as those ofsoftware and networking vendors, that rely on CPUs for performance gainsmay improve their performance by leveraging these multi-core CPUs. Thesoftware designed and constructed for a single CPU may be redesignedand/or rewritten to take advantage of a multi-threaded, parallelarchitecture or otherwise a multi-core architecture.

A multi-core architecture of the appliance 200, referred to as nCore ormulti-core technology, allows the appliance in some embodiments to breakthe single core performance barrier and to leverage the power ofmulti-core CPUs. In the previous architecture described in connectionwith FIG. 2A, a single network or packet engine is run. The multiplecores of the nCore technology and architecture allow multiple packetengines to run concurrently and/or in parallel. With a packet enginerunning on each core, the appliance architecture leverages theprocessing capacity of additional cores. In some embodiments, thisprovides up to a 7× increase in performance and scalability.

Illustrated in FIG. 5A are some embodiments of work, task, load ornetwork traffic distribution across one or more processor coresaccording to a type of parallelism or parallel computing scheme, such asfunctional parallelism, data parallelism or flow-based data parallelism.In brief overview, FIG. 5A illustrates embodiments of a multi-coresystem such as an appliance 200′ with n-cores, a total of cores numbers1 through N. In one embodiment, work, load or network traffic can bedistributed among a first core 505A, a second core 505B, a third core505C, a fourth core 505D, a fifth core 505E, a sixth core 505F, aseventh core 505G, and so on such that distribution is across all or twoor more of the n cores 505N (hereinafter referred to collectively ascores 505.) There may be multiple VIPs 275 each running on a respectivecore of the plurality of cores. There may be multiple packet engines 240each running on a respective core of the plurality of cores. Any of theapproaches used may lead to different, varying or similar work load orperformance level 515 across any of the cores. For a functionalparallelism approach, each core may run a different function of thefunctionalities provided by the packet engine, a VIP 275 or appliance200. In a data parallelism approach, data may be paralleled ordistributed across the cores based on the Network Interface Card (NIC)or VIP 275 receiving the data. In another data parallelism approach,processing may be distributed across the cores by distributing dataflows to each core.

In further detail to FIG. 5A, in some embodiments, load, work or networktraffic can be distributed among cores 505 according to functionalparallelism 500. Functional parallelism may be based on each coreperforming one or more respective functions. In some embodiments, afirst core may perform a first function while a second core performs asecond function. In functional parallelism approach, the functions to beperformed by the multi-core system are divided and distributed to eachcore according to functionality. In some embodiments, functionalparallelism may be referred to as task parallelism and may be achievedwhen each processor or core executes a different process or function onthe same or different data. The core or processor may execute the sameor different code. In some cases, different execution threads or codemay communicate with one another as they work. Communication may takeplace to pass data from one thread to the next as part of a workflow.

In some embodiments, distributing work across the cores 505 according tofunctional parallelism 500, can comprise distributing network trafficaccording to a particular function such as network input/outputmanagement (NW I/O) 510A, secure sockets layer (SSL) encryption anddecryption 510B and transmission control protocol (TCP) functions 510C.This may lead to a work, performance or computing load 515 based on avolume or level of functionality being used. In some embodiments,distributing work across the cores 505 according to data parallelism540, can comprise distributing an amount of work 515 based ondistributing data associated with a particular hardware or softwarecomponent. In some embodiments, distributing work across the cores 505according to flow-based data parallelism 520, can comprise distributingdata based on a context or flow such that the amount of work 515A-N oneach core may be similar, substantially equal or relatively evenlydistributed.

In the case of the functional parallelism approach, each core may beconfigured to run one or more functionalities of the plurality offunctionalities provided by the packet engine or VIP of the appliance.For example, core 1 may perform network I/O processing for the appliance200′ while core 2 performs TCP connection management for the appliance.Likewise, core 3 may perform SSL offloading while core 4 may performlayer 7 or application layer processing and traffic management. Each ofthe cores may perform the same function or different functions. Each ofthe cores may perform more than one function. Any of the cores may runany of the functionality or portions thereof identified and/or describedin conjunction with FIGS. 2A and 2B. In this the approach, the workacross the cores may be divided by function in either a coarse-grainedor fine-grained manner. In some cases, as illustrated in FIG. 5A,division by function may lead to different cores running at differentlevels of performance or load 515.

In the case of the functional parallelism approach, each core may beconfigured to run one or more functionalities of the plurality offunctionalities provided by the packet engine of the appliance. Forexample, core 1 may perform network I/O processing for the appliance200′ while core 2 performs TCP connection management for the appliance.Likewise, core 3 may perform SSL offloading while core 4 may performlayer 7 or application layer processing and traffic management. Each ofthe cores may perform the same function or different functions. Each ofthe cores may perform more than one function. Any of the cores may runany of the functionality or portions thereof identified and/or describedin conjunction with FIGS. 2A and 2B. In this the approach, the workacross the cores may be divided by function in either a coarse-grainedor fine-grained manner. In some cases, as illustrated in FIG. 5Adivision by function may lead to different cores running at differentlevels of load or performance.

The functionality or tasks may be distributed in any arrangement andscheme. For example, FIG. 5B illustrates a first core, Core 1 505A,processing applications and processes associated with network I/Ofunctionality 510A. Network traffic associated with network I/O, in someembodiments, can be associated with a particular port number. Thus,outgoing and incoming packets having a port destination associated withNW I/O 510A will be directed towards Core 1 505A which is dedicated tohandling all network traffic associated with the NW I/O port. Similarly,Core 2 505B is dedicated to handling functionality associated with SSLprocessing and Core 4 505D may be dedicated handling all TCP levelprocessing and functionality.

While FIG. 5A illustrates functions such as network I/O, SSL and TCP,other functions can be assigned to cores. These other functions caninclude any one or more of the functions or operations described herein.For example, any of the functions described in conjunction with FIGS. 2Aand 2B may be distributed across the cores on a functionality basis. Insome cases, a first VIP 275A may run on a first core while a second VIP275B with a different configuration may run on a second core. In someembodiments, each core 505 can handle a particular functionality suchthat each core 505 can handle the processing associated with thatparticular function. For example, Core 2 505B may handle SSL offloadingwhile Core 4 505D may handle application layer processing and trafficmanagement.

In other embodiments, work, load or network traffic may be distributedamong cores 505 according to any type and form of data parallelism 540.In some embodiments, data parallelism may be achieved in a multi-coresystem by each core performing the same task or functionally ondifferent pieces of distributed data. In some embodiments, a singleexecution thread or code controls operations on all pieces of data. Inother embodiments, different threads or instructions control theoperation, but may execute the same code. In some embodiments, dataparallelism is achieved from the perspective of a packet engine,vServers (VIPs) 275A-C, network interface cards (NIC) 542D-E and/or anyother networking hardware or software included on or associated with anappliance 200. For example, each core may run the same packet engine orVIP code or configuration but operate on different sets of distributeddata. Each networking hardware or software construct can receivedifferent, varying or substantially the same amount of data, and as aresult may have varying, different or relatively the same amount of load515

In the case of a data parallelism approach, the work may be divided upand distributed based on VIPs, NICs and/or data flows of the VIPs orNICs. In one of these approaches, the work of the multi-core system maybe divided or distributed among the VIPs by having each VIP work on adistributed set of data. For example, each core may be configured to runone or more VIPs. Network traffic may be distributed to the core foreach VIP handling that traffic. In another of these approaches, the workof the appliance may be divided or distributed among the cores based onwhich NIC receives the network traffic. For example, network traffic ofa first NIC may be distributed to a first core while network traffic ofa second NIC may be distributed to a second core. In some cases, a coremay process data from multiple NICs.

While FIG. 5A illustrates a single vServer associated with a single core505, as is the case for VIP1 275A, VIP2 275B and VIP3 275C. In someembodiments, a single vServer can be associated with one or more cores505. In contrast, one or more vServers can be associated with a singlecore 505. Associating a vServer with a core 505 may include that core505 to process all functions associated with that particular vServer. Insome embodiments, each core executes a VIP having the same code andconfiguration. In other embodiments, each core executes a VIP having thesame code but different configuration. In some embodiments, each coreexecutes a VIP having different code and the same or differentconfiguration.

Like vServers, NICs can also be associated with particular cores 505. Inmany embodiments, NICs can be connected to one or more cores 505 suchthat when a NIC receives or transmits data packets, a particular core505 handles the processing involved with receiving and transmitting thedata packets. In one embodiment, a single NIC can be associated with asingle core 505, as is the case with NIC1 542D and NIC2 542E. In otherembodiments, one or more NICs can be associated with a single core 505.In other embodiments, a single NIC can be associated with one or morecores 505. In these embodiments, load could be distributed amongst theone or more cores 505 such that each core 505 processes a substantiallysimilar amount of load. A core 505 associated with a NIC may process allfunctions and/or data associated with that particular NIC.

While distributing work across cores based on data of VIPs or NICs mayhave a level of independency, in some embodiments, this may lead tounbalanced use of cores as illustrated by the varying loads 515 of FIG.5A.

In some embodiments, load, work or network traffic can be distributedamong cores 505 based on any type and form of data flow. In another ofthese approaches, the work may be divided or distributed among coresbased on data flows. For example, network traffic between a client and aserver traversing the appliance may be distributed to and processed byone core of the plurality of cores. In some cases, the core initiallyestablishing the session or connection may be the core for which networktraffic for that session or connection is distributed. In someembodiments, the data flow is based on any unit or portion of networktraffic, such as a transaction, a request/response communication ortraffic originating from an application on a client. In this manner andin some embodiments, data flows between clients and servers traversingthe appliance 200′ may be distributed in a more balanced manner than theother approaches.

In flow-based data parallelism 520, distribution of data is related toany type of flow of data, such as request/response pairings,transactions, sessions, connections or application communications. Forexample, network traffic between a client and a server traversing theappliance may be distributed to and processed by one core of theplurality of cores. In some cases, the core initially establishing thesession or connection may be the core for which network traffic for thatsession or connection is distributed. The distribution of data flow maybe such that each core 505 carries a substantially equal or relativelyevenly distributed amount of load, data or network traffic.

In some embodiments, the data flow is based on any unit or portion ofnetwork traffic, such as a transaction, a request/response communicationor traffic originating from an application on a client. In this mannerand in some embodiments, data flows between clients and serverstraversing the appliance 200′ may be distributed in a more balancedmanner than the other approached. In one embodiment, data flow can bedistributed based on a transaction or a series of transactions. Thistransaction, in some embodiments, can be between a client and a serverand can be characterized by an IP address or other packet identifier.For example, Core 1 505A can be dedicated to transactions between aparticular client and a particular server, therefore the load 536A onCore 1 505A may be comprised of the network traffic associated with thetransactions between the particular client and server. Allocating thenetwork traffic to Core 1 505A can be accomplished by routing all datapackets originating from either the particular client or server to Core1 505A.

While work or load can be distributed to the cores based in part ontransactions, in other embodiments load or work can be allocated on aper packet basis. In these embodiments, the appliance 200 can interceptdata packets and allocate them to a core 505 having the least amount ofload. For example, the appliance 200 could allocate a first incomingdata packet to Core 1 505A because the load 536A on Core 1 is less thanthe load 536B-N on the rest of the cores 505B-N. Once the first datapacket is allocated to Core 1 505A, the amount of load 536A on Core 1505A is increased proportional to the amount of processing resourcesneeded to process the first data packet. When the appliance 200intercepts a second data packet, the appliance 200 will allocate theload to Core 4 505D because Core 4 505D has the second least amount ofload. Allocating data packets to the core with the least amount of loadcan, in some embodiments, ensure that the load 536A-N distributed toeach core 505 remains substantially equal.

In other embodiments, load can be allocated on a per unit basis where asection of network traffic is allocated to a particular core 505. Theabove-mentioned example illustrates load balancing on a per/packetbasis. In other embodiments, load can be allocated based on a number ofpackets such that every 10, 100 or 1000 packets are allocated to thecore 505 having the least amount of load. The number of packetsallocated to a core 505 can be a number determined by an application,user or administrator and can be any number greater than zero. In stillother embodiments, load can be allocated based on a time metric suchthat packets are distributed to a particular core 505 for apredetermined amount of time. In these embodiments, packets can bedistributed to a particular core 505 for five milliseconds or for anyperiod of time determined by a user, program, system, administrator orotherwise. After the predetermined time period elapses, data packets aretransmitted to a different core 505 for the predetermined period oftime.

Flow-based data parallelism methods for distributing work, load ornetwork traffic among the one or more cores 505 can comprise anycombination of the above-mentioned embodiments. These methods can becarried out by any part of the appliance 200, by an application or setof executable instructions executing on one of the cores 505, such asthe packet engine, or by any application, program or agent executing ona computing device in communication with the appliance 200.

The functional and data parallelism computing schemes illustrated inFIG. 5A can be combined in any manner to generate a hybrid parallelismor distributed processing scheme that encompasses function parallelism500, data parallelism 540, flow-based data parallelism 520 or anyportions thereof. In some cases, the multi-core system may use any typeand form of load balancing schemes to distribute load among the one ormore cores 505. The load balancing scheme may be used in any combinationwith any of the functional and data parallelism schemes or combinationsthereof.

Illustrated in FIG. 5B is an embodiment of a multi-core system 545,which may be any type and form of one or more systems, appliances,devices or components. This system 545, in some embodiments, can beincluded within an appliance 200 having one or more processing cores505A-N. The system 545 can further include one or more packet engines(PE) or packet processing engines (PPE) 548A-N communicating with amemory bus 556. The memory bus may be used to communicate with the oneor more processing cores 505A-N. Also included within the system 545 canbe one or more network interface cards (NIC) 552 and a flow distributor550 which can further communicate with the one or more processing cores505A-N. The flow distributor 550 can comprise a Receive Side Scaler(RSS) or Receive Side Scaling (RSS) module 560.

Further referring to FIG. 5B, and in more detail, in one embodiment thepacket engine(s) 548A-N can comprise any portion of the appliance 200described herein, such as any portion of the appliance described inFIGS. 2A and 2B. The packet engine(s) 548A-N can, in some embodiments,comprise any of the following elements: the packet engine 240, a networkstack 267; a cache manager 232; a policy engine 236; a compressionengine 238; an encryption engine 234; a GUI 210; a CLI 212; shellservices 214; monitoring programs 216; and any other software orhardware element able to receive data packets from one of either thememory bus 556 or the one of more cores 505A-N. In some embodiments, thepacket engine(s) 548A-N can comprise one or more vServers 275A-N, or anyportion thereof. In other embodiments, the packet engine(s) 548A-N canprovide any combination of the following functionalities: SSL VPN 280;Intranet UP 282; switching 284; DNS 286; packet acceleration 288; App FW280; monitoring such as the monitoring provided by a monitoring agent197; functionalities associated with functioning as a TCP stack; loadbalancing; SSL offloading and processing; content switching; policyevaluation; caching; compression; encoding; decompression; decoding;application firewall functionalities; XML processing and acceleration;and SSL VPN connectivity.

The packet engine(s) 548A-N can, in some embodiments, be associated witha particular server, user, client or network. When a packet engine 548becomes associated with a particular entity, that packet engine 548 canprocess data packets associated with that entity. For example, should apacket engine 548 be associated with a first user, that packet engine548 will process and operate on packets generated by the first user, orpackets having a destination address associated with the first user.Similarly, the packet engine 548 may choose not to be associated with aparticular entity such that the packet engine 548 can process andotherwise operate on any data packets not generated by that entity ordestined for that entity.

In some instances, the packet engine(s) 548A-N can be configured tocarry out the any of the functional and/or data parallelism schemesillustrated in FIG. 5A. In these instances, the packet engine(s) 548A-Ncan distribute functions or data among the processing cores 505A-N sothat the distribution is according to the parallelism or distributionscheme. In some embodiments, a single packet engine(s) 548A-N carriesout a load balancing scheme, while in other embodiments one or morepacket engine(s) 548A-N carry out a load balancing scheme. Each core505A-N, in one embodiment, can be associated with a particular packetengine 505 such that load balancing can be carried out by the packetengine 505. Load balancing may in this embodiment, require that eachpacket engine 505 associated with a core 505 communicate with the otherpacket engines 505 associated with cores 505 so that the packet engines505 can collectively determine where to distribute load. One embodimentof this process can include an arbiter that receives votes from eachpacket engine 505 for load. The arbiter can distribute load to eachpacket engine 505 based in part on the age of the engine's vote and insome cases a priority value associated with the current amount of loadon an engine's associated core 505.

Any of the packet engines running on the cores may run in user mode,kernel or any combination thereof. In some embodiments, the packetengine operates as an application or program running is user orapplication space. In these embodiments, the packet engine may use anytype and form of interface to access any functionality provided by thekernel. In some embodiments, the packet engine operates in kernel modeor as part of the kernel. In some embodiments, a first portion of thepacket engine operates in user mode while a second portion of the packetengine operates in kernel mode. In some embodiments, a first packetengine on a first core executes in kernel mode while a second packetengine on a second core executes in user mode. In some embodiments, thepacket engine or any portions thereof operates on or in conjunction withthe NIC or any drivers thereof.

In some embodiments the memory bus 556 can be any type and form ofmemory or computer bus. While a single memory bus 556 is depicted inFIG. 5B, the system 545 can comprise any number of memory buses 556. Inone embodiment, each packet engine 548 can be associated with one ormore individual memory buses 556.

The NIC 552 can in some embodiments be any of the network interfacecards or mechanisms described herein. The NIC 552 can have any number ofports. The NIC can be designed and constructed to connect to any typeand form of network 104. While a single NIC 552 is illustrated, thesystem 545 can comprise any number of NICs 552. In some embodiments,each core 505A-N can be associated with one or more single NICs 552.Thus, each core 505 can be associated with a single NIC 552 dedicated toa particular core 505.

The cores 505A-N can comprise any of the processors described herein.Further, the cores 505A-N can be configured according to any of the core505 configurations described herein. Still further, the cores 505A-N canhave any of the core 505 functionalities described herein. While FIG. 5Billustrates seven cores 505A-G, any number of cores 505 can be includedwithin the system 545. In particular, the system 545 can comprise “N”cores, where “N” is a whole number greater than zero.

A core may have or use memory that is allocated or assigned for use tothat core. The memory may be considered private or local memory of thatcore and only accessible by that core. A core may have or use memorythat is shared or assigned to multiple cores. The memory may beconsidered public or shared memory that is accessible by more than onecore. A core may use any combination of private and public memory. Withseparate address spaces for each core, some level of coordination iseliminated from the case of using the same address space. With aseparate address space, a core can perform work on information and datain the core's own address space without worrying about conflicts withother cores. Each packet engine may have a separate memory pool for TCPand/or SSL connections.

Further referring to FIG. 5B, any of the functionality and/orembodiments of the cores 505 described above in connection with FIG. 5Acan be deployed in any embodiment of the virtualized environmentdescribed above in connection with FIGS. 4A and 4B. Instead of thefunctionality of the cores 505 being deployed in the form of a physicalprocessor 505, such functionality may be deployed in a virtualizedenvironment 400 on any computing device 100, such as a client 102,server 106 or appliance 200. In other embodiments, instead of thefunctionality of the cores 505 being deployed in the form of anappliance or a single device, the functionality may be deployed acrossmultiple devices in any arrangement. For example, one device maycomprise two or more cores and another device may comprise two or morecores. For example, a multi-core system may include a cluster ofcomputing devices, a server farm or network of computing devices. Insome embodiments, instead of the functionality of the cores 505 beingdeployed in the form of cores, the functionality may be deployed on aplurality of processors, such as a plurality of single core processors.

In one embodiment, the cores 505 may be any type and form of processor.In some embodiments, a core can function substantially similar to anyprocessor or central processing unit described herein. In someembodiment, the cores 505 may comprise any portion of any processordescribed herein. While FIG. 5A illustrates seven cores, there can existany “N” number of cores within an appliance 200, where “N” is any wholenumber greater than one. In some embodiments, the cores 505 can beinstalled within a common appliance 200, while in other embodiments thecores 505 can be installed within one or more appliance(s) 200communicatively connected to one another. The cores 505 can in someembodiments comprise graphics processing software, while in otherembodiments the cores 505 provide general processing capabilities. Thecores 505 can be installed physically near each other and/or can becommunicatively connected to each other. The cores may be connected byany type and form of bus or subsystem physically and/or communicativelycoupled to the cores for transferring data between to, from and/orbetween the cores.

While each core 505 can comprise software for communicating with othercores, in some embodiments a core manager (Not Shown) can facilitatecommunication between each core 505. In some embodiments, the kernel mayprovide core management. The cores may interface or communicate witheach other using a variety of interface mechanisms. In some embodiments,core to core messaging may be used to communicate between cores, such asa first core sending a message or data to a second core via a bus orsubsystem connecting the cores. In some embodiments, cores maycommunicate via any type and form of shared memory interface. In oneembodiment, there may be one or more memory locations shared among allthe cores. In some embodiments, each core may have separate memorylocations shared with each other core. For example, a first core mayhave a first shared memory with a second core and a second share memorywith a third core. In some embodiments, cores may communicate via anytype of programming or API, such as function calls via the kernel. Insome embodiments, the operating system may recognize and supportmultiple core devices and provide interfaces and API for inter-corecommunications.

The flow distributor 550 can be any application, program, library,script, task, service, process or any type and form of executableinstructions executing on any type and form of hardware. In someembodiments, the flow distributor 550 may any design and construction ofcircuitry to perform any of the operations and functions describedherein. In some embodiments, the flow distributor distribute, forwards,routes, controls and/ors manage the distribution of data packets amongthe cores 505 and/or packet engine or VIPs running on the cores. Theflow distributor 550, in some embodiments, can be referred to as aninterface master. In one embodiment, the flow distributor 550 comprisesa set of executable instructions executing on a core or processor of theappliance 200. In another embodiment, the flow distributor 550 comprisesa set of executable instructions executing on a computing machine incommunication with the appliance 200. In some embodiments, the flowdistributor 550 comprises a set of executable instructions executing ona NIC, such as firmware. In still other embodiments, the flowdistributor 550 comprises any combination of software and hardware todistribute data packets among cores or processors. In one embodiment,the flow distributor 550 executes on at least one of the cores 505A-N,while in other embodiments a separate flow distributor 550 assigned toeach core 505A-N executes on an associated core 505A-N. The flowdistributor may use any type and form of statistical or probabilisticalgorithms or decision making to balance the flows across the cores. Thehardware of the appliance, such as a NIC, or the kernel may be designedand constructed to support sequential operations across the NICs and/orcores.

In embodiments where the system 545 comprises one or more flowdistributors 550, each flow distributor 550 can be associated with aprocessor 505 or a packet engine 548. The flow distributors 550 cancomprise an interface mechanism that allows each flow distributor 550 tocommunicate with the other flow distributors 550 executing within thesystem 545. In one instance, the one or more flow distributors 550 candetermine how to balance load by communicating with each other. Thisprocess can operate substantially similarly to the process describedabove for submitting votes to an arbiter which then determines whichflow distributor 550 should receive the load. In other embodiments, afirst flow distributor 550′ can identify the load on an associated coreand determine whether to forward a first data packet to the associatedcore based on any of the following criteria: the load on the associatedcore is above a predetermined threshold; the load on the associated coreis below a predetermined threshold; the load on the associated core isless than the load on the other cores; or any other metric that can beused to determine where to forward data packets based in part on theamount of load on a processor.

The flow distributor 550 can distribute network traffic among the cores505 according to a distribution, computing or load balancing scheme suchas those described herein. In one embodiment, the flow distributor candistribute network traffic or; pad according to any one of a functionalparallelism distribution scheme 550, a data parallelism loaddistribution scheme 540, a flow-based data parallelism distributionscheme 520, or any combination of these distribution scheme or any loadbalancing scheme for distributing load among multiple processors. Theflow distributor 550 can therefore act as a load distributor by takingin data packets and distributing them across the processors according toan operative load balancing or distribution scheme. In one embodiment,the flow distributor 550 can comprise one or more operations, functionsor logic to determine how to distribute packers, work or loadaccordingly. In still other embodiments, the flow distributor 550 cancomprise one or more sub operations, functions or logic that canidentify a source address and a destination address associated with adata packet, and distribute packets accordingly.

In some embodiments, the flow distributor 550 can comprise areceive-side scaling (RSS) network driver, module 560 or any type andform of executable instructions which distribute data packets among theone or more cores 505. The RSS module 560 can comprise any combinationof hardware and software, In some embodiments, the RSS module 560 worksin conjunction with the flow distributor 550 to distribute data packetsacross the cores 505A-N or among multiple processors in amulti-processor network. The RSS module 560 can execute within the NIC552 in some embodiments, and in other embodiments can execute on any oneof the cores 505.

In some embodiments, the RSS module 560 uses the MICROSOFTreceive-side-scaling (RSS) scheme. In one embodiment, RSS is a MicrosoftScalable Networking initiative technology that enables receiveprocessing to be balanced across multiple processors in the system whilemaintaining in-order delivery of the data. The RSS may use any type andform of hashing scheme to determine a core or processor for processing anetwork packet.

The RSS module 560 can apply any type and form hash function such as theToeplitz hash function. The hash function may be applied to the hashtype or any the sequence of values. The hash function may be a securehash of any security level or is otherwise cryptographically secure. Thehas function may use a hash key. The size of the key is dependent uponthe hash function. For the Toeplitz hash, the size may be 40 bytes forIPv6 and 16 bytes for IPv4.

The hash function may be designed and constructed based on any one ormore criteria or design goals. In some embodiments, a hash function maybe used that provides an even distribution of hash result for differenthash inputs and different hash types, including TCP/IPv4, TCP/IPv6,IPv4, and IPv6 headers. In some embodiments, a hash function may be usedthat provides a hash result that is evenly distributed when a smallnumber of buckets are present (for example, two or four). In someembodiments, hash function may be used that provides a hash result thatis randomly distributed when a large number of buckets were present (forexample, 64 buckets). In some embodiments, the hash function isdetermined based on a level of computational or resource usage. In someembodiments, the hash function is determined based on ease or difficultyof implementing the hash in hardware. In some embodiments, the hashfunction is determined bases on the ease or difficulty of a maliciousremote host to send packets that would all hash to the same bucket.

The RSS may generate hashes from any type and form of input, such as asequence of values. This sequence of values can include any portion ofthe network packet, such as any header, field or payload of networkpacket, or portions thereof. In some embodiments, the input to the hashmay be referred to as a hash type and include any tuples of informationassociated with a network packet or data flow, such as any of thefollowing: a four tuple comprising at least two IP addresses and twoports; a four tuple comprising any four sets of values; a six tuple; atwo tuple; and/or any other sequence of numbers or values. The followingare example of hash types that may be used by RSS:

4-tuple of source TCP Port, source IP version 4 (IPv4) address,destination TCP Port, and destination IPv4 address. This is the onlyrequired hash type to support.

4-tuple of source TCP Port, source IP version 6 (IPv6) address,destination TCP Port, and destination IPv6 address.

2-tuple of source IPv4 address, and destination IPv4 address.

2-tuple of source IPv6 address, and destination IPv6 address.

2-tuple of source IPv6 address, and destination IPv6 address, includingsupport for parsing IPv6 extension headers.

The hash result or any portion thereof may used to identify a core orentity, such as a packet engine or VIP, for distributing a networkpacket. In some embodiments, one or more hash bits or mask are appliedto the hash result. The hash bit or mask may be any number of bits orbytes. A NIC may support any number of bits, such as seven bits. Thenetwork stack may set the actual number of bits to be used duringinitialization. The number will be between 1 and 7, inclusive.

The hash result may be used to identify the core or entity via any typeand form of table, such as a bucket table or indirection table. In someembodiments, the number of hash-result bits are used to index into thetable. The range of the hash mask may effectively define the size of theindirection table. Any portion of the hash result or the hast resultitself may be used to index the indirection table. The values in thetable may identify any of the cores or processor, such as by a core orprocessor identifier. In some embodiments, all of the cores of themulti-core system are identified in the table. In other embodiments, aport of the cores of the multi-core system are identified in the table.The indirection table may comprise any number of buckets for example 2to 128 buckets that may be indexed by a hash mask. Each bucket maycomprise a range of index values that identify a core or processor. Insome embodiments, the flow controller and/or RSS module may rebalancethe network rebalance the network load by changing the indirectiontable.

In some embodiments, the multi-core system 575 does not include a RSSdriver or RSS module 560. In some of these embodiments, a softwaresteering module (Not Shown) or a software embodiment of the RSS modulewithin the system can operate in conjunction with or as part of the flowdistributor 550 to steer packets to cores 505 within the multi-coresystem 575.

The flow distributor 550, in some embodiments, executes within anymodule or program on the appliance 200, on any one of the cores 505 andon any one of the devices or components included within the multi-coresystem 575. In some embodiments, the flow distributor 550′ can executeon the first core 505A, while in other embodiments the flow distributor550″ can execute on the NIC 552. In still other embodiments, an instanceof the flow distributor 550′ can execute on each core 505 included inthe multi-core system 575. In this embodiment, each instance of the flowdistributor 550′ can communicate with other instances of the flowdistributor 550′ to forward packets back and forth across the cores 505.There exist situations where a response to a request packet may not beprocessed by the same core, i.e. the first core processes the requestwhile the second core processes the response. In these situations, theinstances of the flow distributor 550′ can intercept the packet andforward it to the desired or correct core 505, i.e. a flow distributorinstance 550′ can forward the response to the first core. Multipleinstances of the flow distributor 550′ can execute on any number ofcores 505 and any combination of cores 505.

The flow distributor may operate responsive to any one or more rules orpolicies. The rules may identify a core or packet processing engine toreceive a network packet, data or data flow. The rules may identify anytype and form of tuple information related to a network packet, such asa 4-tuple of source and destination IP address and source anddestination ports. Based on a received packet matching the tuplespecified by the rule, the flow distributor may forward the packet to acore or packet engine. In some embodiments, the packet is forwarded to acore via shared memory and/or core to core messaging.

Although FIG. 5B illustrates the flow distributor 550 as executingwithin the multi-core system 575, in some embodiments the flowdistributor 550 can execute on a computing device or appliance remotelylocated from the multi-core system 575. In such an embodiment, the flowdistributor 550 can communicate with the multi-core system 575 to takein data packets and distribute the packets across the one or more cores505. The flow distributor 550 can, in one embodiment, receive datapackets destined for the appliance 200, apply a distribution scheme tothe received data packets and distribute the data packets to the one ormore cores 505 of the multi-core system 575. In one embodiment, the flowdistributor 550 can be included in a router or other appliance such thatthe router can target particular cores 505 by altering meta dataassociated with each packet so that each packet is targeted towards asub-node of the multi-core system 575. In such an embodiment, CISCO'svn-tag mechanism can be used to alter or tag each packet with theappropriate meta data.

Illustrated in FIG. 5C is an embodiment of a multi-core system 575comprising one or more processing cores 505A-N. In brief overview, oneof the cores 505 can be designated as a control core 505A and can beused as a control plane 570 for the other cores 505. The other cores maybe secondary cores which operate in a data plane while the control coreprovides the control plane. The cores 505A-N may share a global cache580. While the control core provides a control plane, the other cores inthe multi-core system form or provide a data plane. These cores performdata processing functionality on network traffic while the controlprovides initialization, configuration and control of the multi-coresystem.

Further referring to FIG. 5C, and in more detail, the cores 505A-N aswell as the control core 505A can be any processor described herein.Furthermore, the cores 505A-N and the control core 505A can be anyprocessor able to function within the system 575 described in FIG. 5C.Still further, the cores 505A-N and the control core 505A can be anycore or group of cores described herein. The control core may be adifferent type of core or processor than the other cores. In someembodiments, the control may operate a different packet engine or have apacket engine configured differently than the packet engines of theother cores.

Any portion of the memory of each of the cores may be allocated to orused for a global cache that is shared by the cores. In brief overview,a predetermined percentage or predetermined amount of each of the memoryof each core may be used for the global cache. For example, 50% of eachmemory of each code may be dedicated or allocated to the shared globalcache. That is, in the illustrated embodiment, 2 GB of each coreexcluding the control plane core or core 1 may be used to form a 28 GBshared global cache. The configuration of the control plane such as viathe configuration services may determine the amount of memory used forthe shared global cache. In some embodiments, each core may provide adifferent amount of memory for use by the global cache. In otherembodiments, any one core may not provide any memory or use the globalcache. In some embodiments, any of the cores may also have a local cachein memory not allocated to the global shared memory. Each of the coresmay store any portion of network traffic to the global shared cache.Each of the cores may check the cache for any content to use in arequest or response. Any of the cores may obtain content from the globalshared cache to use in a data flow, request or response.

The global cache 580 can be any type and form of memory or storageelement, such as any memory or storage element described herein. In someembodiments, the cores 505 may have access to a predetermined amount ofmemory (i.e. 32 GB or any other memory amount commensurate with thesystem 575.) The global cache 580 can be allocated from thatpredetermined amount of memory while the rest of the available memorycan be allocated among the cores 505. In other embodiments, each core505 can have a predetermined amount of memory. The global cache 580 cancomprise an amount of the memory allocated to each core 505. This memoryamount can be measured in bytes, or can be measured as a percentage ofthe memory allocated to each core 505. Thus, the global cache 580 cancomprise 1 GB of memory from the memory associated with each core 505,or can comprise 20 percent or one-half of the memory associated witheach core 505. In some embodiments, only a portion of the cores 505provide memory to the global cache 580, while in other embodiments theglobal cache 580 can comprise memory not allocated to the cores 505.

Each core 505 can use the global cache 580 to store network traffic orcache data. In some embodiments, the packet engines of the core use theglobal cache to cache and use data stored by the plurality of packetengines. For example, the cache manager of FIG. 2A and cachefunctionality of FIG. 2B may use the global cache to share data foracceleration. For example, each of the packet engines may storeresponses, such as HTML data, to the global cache. Any of the cachemanagers operating on a core may access the global cache to servercaches responses to client requests.

In some embodiments, the cores 505 can use the global cache 580 to storea port allocation table which can be used to determine data flow basedin part on ports. In other embodiments, the cores 505 can use the globalcache 580 to store an address lookup table or any other table or listthat can be used by the flow distributor to determine where to directincoming and outgoing data packets. The cores 505 can, in someembodiments read from and write to cache 580, while in other embodimentsthe cores 505 can only read from or write to cache 580. The cores mayuse the global cache to perform core to core communications.

The global cache 580 may be sectioned into individual memory sectionswhere each section can be dedicated to a particular core 505. In oneembodiment, the control core 505A can receive a greater amount ofavailable cache, while the other cores 505 can receiving varying amountsor access to the global cache 580.

In some embodiments, the system 575 can comprise a control core 505A.While FIG. 5C illustrates core 1 505A as the control core, the controlcore can be any core within the appliance 200 or multi-core system.Further, while only a single control core is depicted, the system 575can comprise one or more control cores each having a level of controlover the system. In some embodiments, one or more control cores can eachcontrol a particular aspect of the system 575. For example, one core cancontrol deciding which distribution scheme to use, while another corecan determine the size of the global cache 580.

The control plane of the multi-core system may be the designation andconfiguration of a core as the dedicated management core or as a mastercore. This control plane core may provide control, management andcoordination of operation and functionality the plurality of cores inthe multi-core system. This control plane core may provide control,management and coordination of allocation and use of memory of thesystem among the plurality of cores in the multi-core system, includinginitialization and configuration of the same. In some embodiments, thecontrol plane includes the flow distributor for controlling theassignment of data flows to cores and the distribution of networkpackets to cores based on data flows. In some embodiments, the controlplane core runs a packet engine and in other embodiments, the controlplane core is dedicated to management and control of the other cores ofthe system.

The control core 505A can exercise a level of control over the othercores 505 such as determining how much memory should be allocated toeach core 505 or determining which core 505 should be assigned to handlea particular function or hardware/software entity. The control core505A, in some embodiments, can exercise control over those cores 505within the control plan 570. Thus, there can exist processors outside ofthe control plane 570 which are not controlled by the control core 505A.Determining the boundaries of the control plane 570 can includemaintaining, by the control core 505A or agent executing within thesystem 575, a list of those cores 505 controlled by the control core505A. The control core 505A can control any of the following:initialization of a core; determining when a core is unavailable;re-distributing load to other cores 505 when one core fails; determiningwhich distribution scheme to implement; determining which core shouldreceive network traffic; determining how much cache should be allocatedto each core; determining whether to assign a particular function orelement to a particular core; determining whether to permit cores tocommunicate with one another; determining the size of the global cache580; and any other determination of a function, configuration oroperation of the cores within the system 575.

F. Systems and Methods for Rewriting a Stream of Data Via anIntermediary

Illustrated in FIGS. 6A and 6B are embodiments of a system that usesstreaming rewrite. The system can include one or more users accessing anappliance via one or more client devices. The appliance can furthercommunicate with one or more backend servers.

Further referring to FIGS. 6A and 6B, and in more detail, in oneembodiment the system can include one or more users accessing anappliance via one or more clients. The clients can be any computer, andin some embodiments can be any computing device 100 described herein. Insome embodiments, the clients can be an appliance, a server or any othercomputing machine. Users accessing the appliance via the one or moreclients can issue requests using one or more user interfaces displayedon the one or more clients. In some embodiments, a client generates arequest in response to client information entered in a user interfacedisplayed on the client. In some embodiments, the request can be a HTTPrequest.

The appliance can be any appliance, and in some embodiments can be anyappliance 200 described herein. In some embodiments, the appliance 200can include a multi-core system 545.

In one embodiment, the appliance can communicate with one or morebackend servers. The backend servers, in one embodiment, can be anyserver. In another embodiment, the backend servers can be any serverdescribed herein. The backend servers, in some embodiments, can receivethe HTTP request and generate and issue a HTTP response. Upon receivingthe HTTP response, the appliance can forward the HTTP response to theone or more clients.

FIG. 6A illustrates an embodiment of the system where a rewrite can beperformed by the appliance. In this embodiment, the rewrite may includereplacing the phrase or pattern “http” with the phrase or pattern“https.” In some embodiments, the appliance can rewrite data packets asthey are received at the appliance. Upon rewriting the packets, theappliance can forward the packets to the backend servers. In otherembodiments, the appliance can rewrite the HTTP requests issued by theclients as they are received on the appliance. Upon rewriting the HTTPrequest, the appliance can forward the request to the backend server.

In some embodiments, the content that is rewritten by the appliance canbe content defined in part by a set of actions. These actions can betriggered by a set of policies that are configured on the appliance. Forexample, an action could indicate that all occurrences of the phrase orpattern “HTTP://” in a response body need be replaced with the phrase orpattern “HTTPS://.” The appliance, in some embodiments, can then copyeach response body to a buffer, parse the body for the required pattern,and rewrite the portion of the response that contains the requiredpattern. While FIGS. 6A and 6B illustrate a single action that dictatesrewriting a single pattern or phrase, the rewrite process can includemultiple actions where each action can specify one or more patterns orphrases to be rewritten by the appliance. In many embodiments, theappliance parses the body of the packet, response or request beforerewriting the indicated pattern.

Illustrated in FIG. 6B is one embodiment of a system where a barrierbyte is used. In some embodiments, the appliance can continue rewritingpackets, responses and/or requests until a barrier byte amount isreached. In some embodiments, a barrier byte can be a sum of a maximumamount of packets that can be held by the appliance. While in someembodiments the barrier byte value can be a fixed value, in otherembodiments the barrier byte value can be automatically configured basedon characteristics of the system. In some embodiments, the barrier bytevalue can be configured by actuating one or more controls on theappliance. In still other embodiments, the barrier byte value can beconfigured via an administrative interface on a display screen of theappliance.

Illustrated in FIG. 6C is one embodiment of a system 600 for rewriting astream of content traversing a device intermediary to a client 102 and aserver 106. In brief overview, the system includes a device 200intermediary to a client 102 and a server 106. The client may be of anycomputing device described herein. The system 600 may include one ormore clients. The server may be of any computing device describedherein. The system 600 may include one or more servers or located in aserver farm. The device 200 may intercept requests 610 and responses 615communicated between the client 102 and the server 106 over a network104. The appliance may include an application firewall 290 which mayinclude a parser 620, a packet engine 548, a rewrite buffer 625, arewriter 630, actions 635, and a database 640. In some embodiments, oneor more of these components may be stored on the appliance 200 butoutside of the firewall 290. In some embodiments, a database manager mayreside on the appliance 200. In some embodiments, the database managermay reside on the appliance 200 but outside of the application firewall290. In some embodiments, the system 600 includes one or more storagedevices for storing the database 640.

Although some of the steps described herein may be identified asperformed by the application firewall 290 or the appliance 200 or bysome component or module of the firewall 290 or device 200, it should beunderstood that any component(s) or module(s) of the system 600 mayperform the same or substantially the same steps in various embodimentswithout departing from the spirit and scope of the invention. Inaddition, although generally described with respect to a database, itshould be recognized that the present systems and methods may operatingon any suitable data structure that allows storing of identifiedpatterns.

The appliance or device 200 may be any device or component of a dataprocessing, management or storage system 600. The device 200 may be anappliance, a gateway or an intermediary device between one or moreclients 102 and/or one or more servers 106. In some embodiments, thedevice 200 is part of a client 102 or a server 106 receiving ortransmitting one or more messages 677. In various embodiments, thedevice 200 may include one or more features of any embodiment of thecomputing device 100, 102, and/or server 106 described above inconnection with 1A-1H, 2A-2B, 3, 4A-4C and 5A-5C. By way of illustrationand not intended to be limiting, device 200 is sometimes described belowas a firewall 290 in the context of applications firewall processing.

The application firewall 290 may include any type or form of hardwareand/or combination of hardware and software. The application firewall290 may include any application, program, library, script, process,task, thread or any type and form of executable instructions thatexecutes on any processor or core of the system. The applicationfirewall 290 may include one or more modules including a parser 620, arewrite buffer 625, a rewriter 630, actions 635, a database 640 and adatabase manager. Any one or more of these modules may have or inheritsome attributes of the application firewall 290. Any one or more ofthese modules may comprise some portion of the application firewall 290,e.g., the hardware or combination of hardware and/or software. Theapplication firewall 290 may receive one or more requests 610 orresponses 615, communications, packets and/or commands from any one ormore: users, programs, processing modules and other devices (e.g., aclient 102 and/or a server 106).

The application firewall 290 may include a transceiver for receiving arequest 610 or a response 615 and/or retransmitting the request 610 or aresponse 615 to a destination (e.g., server 106). The applicationfirewall 290 may receive a request 610 or a response 615 from aplurality of devices, and may process requests 610 or responses 615between any two or more devices in either direction (i.e., providesbidirectional support). The application firewall 290 may be designed,constructed and/or configured to receive, intercept, re-direct, reroute,filter or otherwise process the request 610 or the response 615. Theapplication firewall 290, via the parser 620, may identify, extract orinfer one or more patterns from the one or more request 610 or response615.

A request 610 or a response 615 may be any type or form ofcommunications using any standard, proprietary and/or custom protocol.The request 610 or the response 615 may be part of communicationsbetween devices or communications between modules of a device. Therequest 610 or the response 615 may include commands, headerinformation, payload, credentials, authentication information, userinformation and any other type of transactional information or content.

The parser 620 may be designed, constructed and/or configured toextract, parse for, infer, identify or otherwise process a packet from arequest 610 or a response 615 or any content. The parser 620 maycomprise hardware or any combination of software and hardware. Theparser 620 may include an application, program, library, script,process, task, thread or any type and form of executable instructionsthat executes on one or more processors or cores of the device 200. Insome embodiments, the parser 620 is a universal or multi-syntax/languageparser 620. In other embodiments, the parser 620 is designed andconstructed to process or analyze any one or more specific types ofinformation. In some embodiments, the parser 620 may decrypt,uncompress, perform protocol translation or otherwise process a receivedrequest 610 or response 615.

The rewrite buffer 625 may comprise hardware or any combination ofsoftware and hardware. The rewrite buffer 625 may be stored on theappliance 200. In some embodiments, the rewrite buffer 625 may be acomponent of the application firewall 290. In some embodiments, therewrite buffer is a storage buffer to store identified packets. In someembodiments, the rewrite buffer 625 is a storage buffer that stores datastructures comprising packets. In some embodiments, the rewrite buffer625 may have a predetermined size threshold. In some embodiments, thepredetermined size threshold of the rewrite buffer 625 is determined attime of manufacture. In some embodiments, the predetermined sizethreshold is set by an administrator of the system 600. In someembodiments, the rewrite buffer 625 may be stored on a storage deviceassociated with the appliance 200.

The rewriter 630 may be designed, constructed and/or configured tomodify, update, generate, identify, or otherwise process a packet from arequest 610 or a response 615 or any content. The rewriter 630 maycomprise hardware or any combination of software and hardware. Therewriter 630 may include an application, program, library, script,process, task, thread or any type and form of executable instructionsthat executes on one or more processors or cores of the device 200. Inother embodiments, the rewriter 630 is designed and constructed toprocess or analyze any one or more specific types of information. Insome embodiments, the rewriter 630 may generate a new packet for anidentified packet using one or more identified patterns provided by thedevice 200. In some embodiments, the rewriter using a first pattern toidentify content to rewrite in the packet. The rewriter 630 then createsa new packet using data from the identified packet and replaces thefirst pattern. In some embodiments, the first pattern is replaced by asecond pattern. In some embodiments, the rewriter replaces the firstpattern with user-supplied content. In some embodiments, the rewriterreplaces the first pattern with content supplied by an action, rule orpolicy of the device. The rewriter, in some embodiments, completesgenerating a new packet and deletes the existing packet.

In some embodiments, the rewriter 630 modifies an existing packet. Therewriter 630 receives the packet to be modified and uses a patternprovided by the device 200 to identify content of the packet to bemodified. In some embodiments, the rewriter 630 uses a patternidentified or provided by the device 200 to identify content to bemodified. In some embodiments, the rewriter 630 deletes the identifiedcontent. In some embodiments, the rewriter 630 replaces the identifiedcontent. In some embodiments, the rewriter 630 replaces the identifiedcontent with another pattern provided by the device 200. In someembodiments, the rewriter 630 replaces the identified content withuser-supplied information. In some embodiments, the rewriter 630replaces the identified content using content provided in an action,rule or policy of the device.

The actions 620 can be represented by or executed by any application,program, library, script, task, service, process or any type and form ofexecutable instructions executing on any type and form of hardware. Insome embodiments, the actions 620 may be any design and construction ofcircuitry to perform any of the operations and functions describedherein. In some embodiments, the actions 620 can comprise a set ofexecutable instructions on the appliance 200. In another embodiment, theactions 620 comprise a set of executable instructions executing on acomputing machine 102, 106 in communication with the appliance 200. Insome embodiments, the actions 620 are a set of executable instructionsexecuting on a NIC, such as firmware. In still other embodiments, theactions 620 comprise any combination of software and hardware to processnetwork packets intercepted from a client 102 or server 106. Actions 620may specify a set of executable instructions to be taken. Examples ofactions 620 may include, without limitation, generating a new packet,removing a packet from the rewrite buffer 625, and storing a data streamderived from a plurality of packets to the rewrite buffer 625.

The database 640 may be designed, constructed and/or configured to storeidentified patterns from packets of a request 610 or a response 615 orany content. The database 640 may comprise hardware or any combinationof software and hardware. The database 640 may be stored on theappliance 200. In some embodiments, the database 640 may be any means ofstoring information, such as table, hash table, or matrix. In someembodiments, the database 640 may be stored on a storage device. In someembodiments, the database may be stored on the server 106.

A database manager of the device 200 may receive one or more stringsfrom the parser 676. The database manager may receive, store, generate,or modify database queries via any type or form of communications, e.g.,core-to-core messaging (CCM) where one core executes the parser 620while the database manager comprises another core. The database managemay be designed, constructed and/or configured to manage a database 640of identified patterns extracted from a response 615 or a request 610.The database manager may evaluate, calculate, translate, transform orotherwise process an identified pattern into a query. The databasemanager may use, employ, invoke or execute any algorithm, method,formula, function, translation device, program, script or command toprocess the identified pattern into a database query. The databasemanager may process each identified pattern for use in a database query.

Illustrated in FIG. 7 is a flow diagram that illustrates one embodimentof a method for carrying out streaming rewrites. In some embodiments, anappliance 200 dechunks a compressed grouping of packets so that theappliance 200 can access each individual packet. A database 640 on theappliance 200 can store one or more interested patterns. In someembodiments, these patterns can be defined in rules or actions 635. Therules and/or actions 635 can be referred to as panstr patterns and canidentify one or more patterns or phrases to rewrite. These patternsand/or phrases can be referred to as the interested patterns.

In some embodiments, the database 640 that stores the patterns, phrases,actions 635 and/or rules can be a panner database 640. This database640, in some embodiments, can be included within a protocol controlblock of the appliance 200. In other embodiments, the panner database640 can be any database, table and/or list that stores information usedto perform the methods and systems described herein. In otherembodiments, the protocol control block and not the panner database 640stores actions 635 to be taken on the dechunked packets. The protocolcontrol block, in some embodiments, can be a connection managementstructure that can manage an appliance's connections with clients 102and/or servers 106.

Upon retrieving the interested patterns from the panner database 640,the appliance 200 can parse the body of each packet for the one or moreinterested patterns. In some embodiments, when the appliance 200identifies a pattern, the appliance 200 rewrites the pattern with thenew pattern identified by the action 6350 in the panner database. Insome embodiments, the rewritten packet can be buffered, additional editscan be applied and the packets can be rechunked together. In someinstances, the appliance 200 can remap the edited packets to a TCPsocket or port before rechunking the packets.

Illustrated in FIG. 8A is one embodiment of a method 800 for performingstreaming rewrites. An appliance can dechunk a group of packets (Step805) and identify actions or rules that further identify one or moresearch patterns (Step 810). A parser executing on the appliance can thenparse the body of one or more packets to identify the search pattern(Step 815). The appliance can then rewrite occurrences of the searchpattern with an identified new pattern (Step 820), and hold the packetsof a partially written response for rewrite (Step 825). The appliancecan then rechunk the packets and transmit the rechunked packets to adestination (Step 830).

Further referring to FIG. 8A, and in more detail, in one embodiment theappliance can dechunk a group of packets (Step 805). Dechunking a groupof packets can include separating a group of compressed and/or encodedpackets. The group of packets, in some embodiments, can correspond to aresponse and/or request. Dechunking the group of packets, in someembodiments, can result in a listing of one or more individual packetsthat together make up an entire response and/or request. Dechunking, insome embodiments can include removing a chunk header from each packet inthe chunk.

The appliance can then identify actions and/or rules that furtheridentify search patterns (Step 810). In some embodiments, the actionsand/or rules can be stored on the appliance 200. In still otherembodiments, the actions 635 and/or rules can be stored within a pannerdatabase 640 on the appliance 200. In one embodiment, the actions and/orrules 635 can hang off of a protocol control block of the appliance 200.The search patterns identified by the actions and/or rules 635 caninclude a pattern to replace and a new pattern to write over the oldpattern. These patterns can be, for example: an indication to replace“http://” with “https://”; an indication to replace “abc.com” with“xyz.com”; and an indication to replace “text” with “Modified.” Thus,the search pattern can include any combination of letters, numbers andsymbols. In one embodiment, the database 640 can include more than oneaction and/or rule. In still other embodiments, the actions and/or rulescan identify one or more search patterns.

Upon identifying one or more search patterns, a parser executing on theappliance can parse the body of each packet for the identified searchpattern (Step 815). In some embodiments, the parser can parse the bodyof a response or request. In still other embodiments, the parser canobtain information about the pattern while parsing the packets for thepattern. The parser can store the obtained pattern information in thepanner database.

In one embodiment, the appliance can rewrite the response and/or packetsto replace the search pattern with the newly identified pattern (Step820). For example, the pattern “abc” can be replaced with the pattern“123.” In some embodiments, the rewrite actions can be performedsubsequent to a lookup in the panner database. Upon identifying patterninformation in the panner database for a particular response and/orpacket, the appliance can either rewrite the response and/or packet, orupdate the panner database and perform the rewrite on any instances ofthe search pattern.

In some embodiments, at least a partial response can be held for rewrite(Step 825). The size of the response held can correspond to a configuredbarrier byte. While FIG. 8 illustrates a method 800 that holds packets,in some embodiments no portion of the response need be held in order fora rewrite to happen. Substantially all rewrite actions can be performedregardless of how much of the response is available for rewrite. In someembodiments, when the amount of memory occupied by held packets exceedsthe barrier byte limit, the oldest held packet can be released therebyfreeing up memory.

Upon rewriting the packets, in some embodiments, the appliance canrechunk the packets and transmit the rechunked packets to a destination(Step 830). In some embodiments, packets may be dechunked and/orrechunked when transfer encoding is employed. Rechunking, in someembodiments, can include adding a modified chunk header to each packetin a chunk. The appliance, in some embodiments, can perform a TCP remapof the packets to a TCP socket or port before rechunking the packets.The destination, in some embodiments, can be any computer, client,server, appliance and/or computing device.

Now referring to FIG. 8B, a flow diagram depicting a method 850 forrewriting a stream of content traversing a device intermediary to aclient and a server is shown. In brief overview, at step 852, a deviceintermediary to clients and a server identifies a plurality of patternsto match for rewriting a stream of content received by the device. Atstep 854, the device performs matching of the plurality of patterns tothe content of the packet via a single parsing of content of a packet.At step 856, the device stores the results of the matching to a databaseassociated with the connection. At step 858, the device stores thepacket to a rewrite buffer with a predetermined size threshold forstoring packet to be rewritten before transmission. At step 860, thedevice performs a rewrite responsive to a determination that the size ofthe rewrite buffer exceeds the predetermined size threshold. The deviceperforms the rewrite on the oldest packet removed from the rewritebuffer based on the results of matching performed on the oldest packetin the database. At step 862, the device transmits the rewritten oldestpacket.

Still referring to FIG. 8B, and in more detail, at step 852, a deviceintermediary to clients and a server identifies a plurality of patternsto match for rewriting a stream of content received by the device. Insome embodiments, the device utilizes an efficient multiple patternsearch algorithm to identify a plurality of patterns. The device maystore these patterns in a panner database 640. In some embodiments, thedevice generates actions responsive to the identification of theplurality of patterns. In some embodiments, the device incorporates theidentified patterns into existing actions and/or rules. In someembodiments, the updated actions or rules are stored in the pannerdatabase 640. If the identified patterns have not been previouslyidentified, the device saves the identified patterns in the pannerdatabase 640. If the identified patterns have been identified in aprevious identification of patterns, then the panner database is notupdated. In some embodiments, the device 200 parses a received httprequest 610 to identify patterns. In some embodiments, the device 200parses a received http response 615 to identify patterns. In someembodiments, the device 200 parses the body of a received http request610 or response 615 and compares the any identified patterns to anexisting rule or action 635. In some embodiments, the device may appendan identified pattern to an existing pattern in a rule or action 635. Insome embodiments, the device may replace an existing pattern of a ruleor action 635 with an identified pattern. In some embodiments, thedevice 200 may replace an existing rule or action 635 with a newlygenerated rule or action which includes one or more of the identifiedpatterns. In some embodiments, the device may receive a response 615from a server 106 to a request 610 of the client 102 through a pluralityof packets. In some embodiments, the payload of each packet of theplurality of packets comprises a portion of a body of the response 615.In some embodiments, the body of the response 615 may be identified in asingle packet. In some embodiments, the body of the request 610 maycomprise a portion of a body of a plurality of packets. In someembodiments, the body of the request 610 may be identified in a singlepacket.

At step 854, the device 200 performs matching of the plurality ofpatterns to the content of the packet via a single parsing of content ofa packet. In some embodiments, the device matches or compares theidentified patterns to the content of a single packet. In someembodiments, multiple patterns may be identified in the single packet.In some embodiments, a single pattern of the plurality of patterns maybe found in the single packet. In some embodiments, none of theidentified patterns of the plurality of patterns may be found in thesingle packet. In some embodiments, the device 200 applies an efficientmultiple pattern search algorithm that parses a received packet. Byapplying a multiple pattern search algorithm, the system 600 may processa packet in a single pass while searching for multiple patterns. In someembodiments, a rule or action 635 may comprise multiple patterns. Therule or action 635 may be applied to a packet and the multiple patternsof the rule may be searched within the packet. In some embodiments,multiple rules or actions 635 each comprising multiple patterns can becombined into a single query and all the patterns from the multiplerules or actions 635 may be searched in a packet in a single pass.

In some embodiments, the system may employ a multiple pattern searchalgorithm. In some embodiments, the system 600 may employ multiplealgorithms, either concurrently or simultaneously. In some embodiments,the system 600 may employ the Boyer-Moore string search algorithm orsome variation of the Boyer-Moore algorithm. In the Boyer-Moorealgorithm, as known in the art, the algorithm verification, or attemptsto check whether a match exists at a particular position, may workbackwards. After checking the last characters of a given string, if theverification fails, the algorithm skips ahead and starts looking for amatch ending at the specified or determined position of the text. Thealgorithm may pre-compute two tables to process the information itobtains in each failed verification. The first able contains informationregarding how many positions ahead to start the next search based on theidentity of the character that caused the match attempt to fail. Thesecond table contains calculation based on how many characters werematched successfully before the match attempt failed. The algorithm mayshift the larger of the two jump values when a mismatch occurs.

In some embodiments, the system 600 may employ the Wu-Manber stringsearch algorithm or some variation of the Wu-Manber algorithm, which isan improvement of the Boyer-Moore algorithm. The Wu-Manber algorithm, asknown in the art, is a multi-stage algorithm that employs three tables:the SHIFT table, HASH table, and PREFIX table. As with the Boyer-Moorealgorithm, the verification, or attempts to check whether a match existsat a particular position, works backwards. The SHIFT table is used todetermine how many characters in the text can be shifted or skipped whenthe text is scanned. The HASH and PREFIX tables are used to determinewhich pattern is a candidate for the match and to verify the match.

In some embodiments, the device 200, may store the packet to a datastructure. In some embodiments, the device 200 stores the packet to adata structure only if the packet contains a matching pattern of theidentified patterns. In some embodiments, the parser 620 parses allreceived packets, regardless of the presence of an identified patternand stores the results of the parsing in a data structure. In someembodiments, the device 200 immediately stores a received packet to adata structure without parsing the packet. In some embodiments, thedevice 200 performs a single parsing of content of the data structure tomatch the plurality of patterns to the content in a single pass.

At step 856, the device stores the results of the matching to a databaseassociated with the connection. In some embodiments, the device 200stores the results of the matching to a database associated with a usersession of a user. In some embodiments, the device 200 stores theresults of the matching to a database 640 stored on the device 200. Insome embodiments, the device 200 stores the results of the matching to adatabase 640 stored on another device accessed by the network 104. Insome embodiments, the device 200 stores the results to a table, a hasttable, a matrix, or other data storage structure. In some embodiments,the database 640 may be a SQL database. In some embodiments, thedatabase 640 may generate a single query using the multiple identifiedpatterns. In some embodiments, the device 200 may generate a new queryresponsive to an identified action 635. In some embodiments, the device200 may generate a new query for each identified pattern. In someembodiments, the device 200 may update an existing query using themultiple identified patterns. In some embodiments, the queries areassociated with an action 635. In some embodiments, the query may bestored on the device 200. In some embodiments, the query may begenerated by a database manager. A database manager may be stored on theappliance 200. In some embodiments, the database manager may executewithin the application firewall 290. In some embodiments, the databasemanager may execute outside of the context of the application firewall290. In some embodiments, the database manager may generate, update andstore all queries for any identified patterns. In some embodiments, thequeries are stored on the device 200. In some embodiments, the queriesare stored on a different device.

At step 858, the device stores the packet to a rewrite buffer with apredetermined size threshold for storing packet to be rewritten beforetransmission. In some embodiments, the device 200 stores only packetswith identified patterns to the rewrite buffer 625. In some embodiments,the device 200 stores the packets to the rewrite buffer responsive to anaction 635 or a policy of the appliance 200. In some embodiments, therewrite buffer 625 has a predetermined size threshold to store data. Insome embodiments, the predetermined size threshold of the rewrite buffer625 is determined at the time of manufacture. In some embodiments, thepredetermined size threshold of the rewrite buffer 625 may be modifiedby an administrator of the system. In some embodiments, thepre-determined size threshold of the rewrite buffer 625 may be modifiedby a user of the system.

At step 860, the device performs a rewrite responsive to a determinationthat the size of the rewrite buffer exceeds the predetermined sizethreshold. The device performs the rewrite on the oldest packet removedfrom the rewrite buffer 625 based on the results of matching performedon the oldest packet in the database 640. In some embodiments, theoldest packet is determined by a timestamp associated with the packet.In some embodiments, a timestamp is stored to the data structure thatholds the packet. In some embodiments, the oldest packet is determinedby the order in which the packet is stored in the rewrite buffer 625. Insome embodiments, packets may be stored not according to timestamp, butaccording to time the device 200 completes processing of the packetprior to storing the packet to the rewrite buffer 625. In someembodiments, the device 200 removes one or more of the oldest packetsfrom the rewrite buffer 625 until the data stored in the rewrite buffer625 is below the predetermined size threshold. In some embodiments, theoldest packets are removed from the rewrite buffer responsive to atriggered action 635 of the device. In some embodiments, the oldestpackets are removed from the rewrite buffer responsive to a policy ofthe device 200. In some embodiments, the rewrite buffer does not permitthe device 200 to store data to the rewrite buffer once thepredetermined threshold has been reached. In some embodiments, thedevice 200, responsive to the inability to store data to the rewritebuffer 635, removes the oldest packet or packets from the rewrite bufferuntil there is enough space to store the refused packet to the rewritebuffer 625.

In some embodiments, the device 200 looks up in the database 640 anoffset into the packet corresponding to a matched pattern to rewrite. Insome embodiments, the device 200 performs the write according to anaction 635 specifying a first pattern to match, a second pattern forreplacing the first pattern and a number of bytes of a body of theresponse to search for the pattern. In some embodiments, the device 200modifies an existing action to identify a pattern in a body and replacethe identified pattern with a second pattern. The second pattern may beanother identified pattern from the previous identification. In someembodiments, the second pattern may be a user-specified pattern. In someembodiments, the second pattern may be an existing pattern from thedatabase 640. In some embodiments, the second pattern may be a patternsupplied by a second action 635, rule or policy of the device 200. Insome embodiments, the second pattern may include multiple identifiedpatterns.

At step 862, the device transmits the rewritten oldest packet. In someembodiments, the device 200 transmits the rewritten oldest packet to theclient 102. In some embodiments, the device 200 transmits the rewrittenoldest packet to the server 106. In some embodiments, the device 200delays transmittal of the rewritten oldest packet according to a policyof the device 200. In some embodiments, the device 200 transmits therewritten oldest packet to its destination immediately. In someembodiments, the device 200 transmits the rewritten oldest packet to adestination stored in the data structure. In some embodiments, thedevice re-routes the rewritten oldest packet responsive to a policy,action 635 or rule of the device 200. In some embodiments, the device200 transmits the rewritten oldest packet to a destination previouslystored in the header of the packet. In some embodiments, the device 200rewrites each of the oldest packets as they are removed from the rewritebuffer 625. In some embodiments, the rewriter 630 removes the oldestpackets from the rewrite buffer 625 and modifies or rewrites the packetusing the identified patterns. In some embodiments, the rewriter 630rewrites the oldest packet responsive to an action 635, policy or ruleof the appliance 200. In some embodiments, the rewriter updates anexisting packet by rewriting portions of the body. In some embodiments,the rewriter 630 generates a new packet using the information from theoldest packet removed from the rewrite buffer 625, deletes the oldestpacket removed from the rewrite buffer 625 and transmits the newlygenerated packet to its destination. In some embodiments, the rewriter630 does not modify or update an existing oldest packet or generate anew packet if the device 200 determines that the packet does not containany of the identified patterns.

G. Systems and Methods for Rewriting a Stream of Data Containing UTF-8Encoding Via an Intermediary

Referring now to FIGS. 9A-9C, systems and methods of efficientlyprocessing, searching and/or rewriting variable width encoded data, suchas UTF-8 encoded data, will be described. Embodiments of the systems andmethods modify and adapt search algorithms, such as the Horspool andWu-Manber algorithms, to efficiently process and manage searching ofvariable width encoded text in large blocks of text, such as text thatmay be carried via a stream of packets thru a network device, such as anintermediary device.

Illustrated in FIGS. 9B and 9C are embodiments of methods of searchtechniques for UTF-8 encoded data. Illustrated in FIG. 9A is anembodiment of a system for performing any of the search techniques forUTF-8 encoded data.

Referring now to FIG. 9A, an embodiment of a system for performing anyof the embodiments of multi-variable encoding search techniquesdescribed herein is depicted. In brief overview, a device 102 mayinclude a search engine 970. The device may receive or obtain a block oftext 980 that includes multi-variable encoded data, such as UTF-8. Thedevice may receive or obtain a search pattern/string 982 ofmulti-variable encoded data to search for within the block of text 980by the search engine. The search engine may implement or include amodified HorSpool 972 component or engine for performing any of themodified HorSpool search techniques for multi-variable encoded datadescribed herein. The search engine may implement or include a modifiedWu Manber 974 component or engine for performing any of the modified WuManber search techniques for multi-variable encoded data describedherein. The search engine may use any of the components 972 and 974 tosearch for the search string 982 within the block of text 980. Thesearch engine may utilize a pointer 990 to locations or positions withinthe block of text, such as stored in memory and move the pointer topivot points 984 responsive to a jump/index table 986 or tables 988,such as shift, hash or prefix tables.

The device 102 may be a client or server device. The device can be anyembodiments of an appliance described herein. The system can include oneor more users accessing an appliance via one or more client devices. Theappliance can further communicate with one or more backend servers. Thesystem for performing any of the methods of FIGS. 9B and 9C can be anyof the systems described herein, such as any embodiments of the streamrewriting appliance described above in Section H.

The device may receive, identify or process a block of text 980. Theblock of text may be a large block of text. The block of text maycomprise a size (in bytes, words, etc.) greater than a predeterminedthreshold. The block of text may comprise any type and form ofmulti-variable encoded data, such as UTF-8 data. The block of text maybe data from a payload of any one or more network packets. The block oftext may comprise application layer data, such as HTTP or HTML datacarried via transport layer packets. The block of text may be data to berewritten by any embodiments of the rewriting systems and methodsdescribed in Section H.

The device may receive, identify or process a search pattern or string983 to search for within the block of text. The search pattern or stringmay comprise any number of characters or symbols. The search pattern orstring may comprise any length. The search pattern or string maycomprise any type and form of multi-variable encoded data, such as UTF-8data. The search pattern or string may be a string or pattern to find oridentify in a payload of any one or more network packets. The searchpattern or string may be a string or pattern to determine whether or notin block of text, such as a payload of any one or more network packets.The search pattern or string may comprise any string or patternidentified by an appliance in a stream of network packets traversing theappliance. The search pattern or string may comprise any string orpattern previously identified by and/or stored by an appliance from astream of network packets traversing the appliance. The search patternor string may be a pattern or string to be rewritten in a block of textby any embodiments of the rewriting systems and methods described inSection H.

The device may receive the block of text and search string via arequest. The device such as via search engine may receive the requestvia an API call. The device such as via search engine may receive therequest via an application layer command, such as via HTML. In someembodiments, the search engine operates in the embodiments of theappliance. In these embodiments, the appliance, such as via a packetengine, use or integrate the search engine, such as via API calls,programmatic instructions, etc. to search for a search string/pattern inthe block of text. In some embodiments, the search engine operates inthe embodiments of the or AppFw 290. In these embodiments, the AppFw mayuse or integrate the search engine, such as via API calls, programmaticinstructions, etc. to search for a search string/pattern in the block oftext.

The search engine 970 may comprise an application, program, library,process, service, task or any type and form of executable instructionsexecuting on a device. The search engine may be designed and constructedto perform any of the search and/or rewriting techniques and embodimentsdescribed herein. The search engine may use pointers 990 to locations orpositions within a block of text, such as to memory address. The searchengine may move the pointer forwards or backwards within the block oftext. The search engine may jump the pointer from one location/addressto another location/address in the block of text, such as response to ajump table. The search engine may jump or move the pointer to a pivotblock, pointer or element 984 which is a point in the block of text. Thepivot block 584 may be defined and used in accordance with theembodiments of the search techniques described herein. The search enginemay apply a search technique, or portion thereof at the pivot element984. A jump table or other table may used to identify pivot points orblocks responsive to an index or table in accordance with the searchtechnique.

The search engine may comprise a Horspool search engine 972 component ormodule. The Horspool search engine may be modified to perform any of themodified Horspool search techniques for multi-variable encoded data,such as UTF-8 encoded data. The Horspool engine may use an index or jumptable 986 for storing information in accordance with the modifiedHorspool search technique. The jump table may comprise a hash to Unicodevalues that identify number of byte lengths for characters. In someembodiments, the jump table may a comprise a has to each correspondinglower case Unicode value that identifies a number of byte lengths forthe corresponding character.

The search engine may comprise a Wu Manber search engine 974 componentor module. The Wu Manber search engine may be modified to perform any ofthe modified Wu Manber search techniques for multi-variable encodeddata, such as UTF-8 encoded data. The Wu Manber engine may use tables988 for storing information in accordance with the modified Wu Manbersearch technique. The Wu-Manber algorithm, component or engine may usethree tables 988: the SHIFT table, HASH table, and PREFIX table. As withthe Boyer-Moore algorithm, the verification, or attempts to checkwhether a match exists at a particular position, works backwards. TheSHIFT table is used to determine how many characters in the text can beshifted or skipped when the text is scanned. The HASH and PREFIX tablesare used to determine which pattern is a candidate for the match and toverify the match.

UTF-8 encoding is a multi-byte character encoding for Unicode. Becauseof its dominate usage by the industry, there is a need for a systemcapable of searching multiple UTF-8 encoded patterns in large blocks oftext. Current systems capable of performing multi-pattern matching arenot capable of performing such searches on encoded text. The followingdescription provides an mechanism that is capable of performingmulti-pattern searching on UTF-8 encoded text.

The Wu Manber search engine component may comprise executableinstructions to perform an adapted, configured or modified Wu Manberbases searching technique for multi-variable encoded data, such as UTF-8encoded data. In some embodiments, the following algorithm is used bythe Wu Manber search engine component to search for case-sensitivemultiple patterns encoded by UTF-8 at the same time. P={p₁, p₂, . . . ,p_(k)} represents a set of patterns, which are strings of charactersfrom a fixed alphabet. Each p_(i) is a string. l_(min) represents theminimum length of a pattern in P in bytes and l_(max) represents themaximum length of a pattern in P in bytes. T={t₁, t₂, . . . t_(N)} is alarge text consisting of characters of the same fixed alphabet as P. Mis the total size of all patterns, where M=k*l_(min) and c is the sizeof the fixed alphabet. The system utilize blocks of three bytes B topreprocess patterns by generating tables. In some embodiments, B maycomprise blocks of fewer than three bytes. In some embodiments, B maycomprise blocks of four bytes.

If the string of B bytes in the text do not appear in any of thepatterns, then the search shifts by l_(min)−B+1. Each string of size Bis mapped to an integer used as an index to the SHIFT table. The valuesin the SHIFT table determine how far to shift while scanning T. Let X=x₁. . . x_(B) is the B characters in the text that are being scanned, andX is mapped into the i′th entry of the SHIFT table. The two cases are:

-   -   If X does not appear as a substring in any pattern in P, then        the search shifts (l_(min)−B+1) bytes. In SHIFT[i], the system        stores (l_(min)−B+1).    -   If X appears as a substring of some patterns of P, the rightmost        occurrence of X in any of the patterns is identified. If X ends        at the position q of P_(j) and assuming that X does not end at        any position greater than q in any other pattern. Then l_(min)−q        is stored in SHIFT[i].

To compute the SHIFT table consider separately each pattern p_(i)=a₁ a₂. . . a_(lmin). Each substring of p_(i) of size B a_(j−b+1) . . . a_(j)is mapped into SHIFT, and the corresponding value is set to the minimumof its current value (the initial value for all of them is l_(min)−B+1)and l_(min)−j (the amount of shifting required to get to thissubstring). During the search phase, the search positions is shiftedalong the text as long as the SHIFT value is positive. When the SHIFTvalue is zero, the text to the left of the search position might be oneof the pattern strings.

The exact same integer to index into another table, called HASH. Thei′th entry of the HASH table, HASH[i], contains a pointer to a list ofpatterns whose last B characters hash into i. The HASH table holds onlythe patterns whereas the SHIFT table holds all possible strings of sizeB.

In some embodiments, the system or search engine may require jumping inthe text. To retain the sub-linear running time complexity, byte jumpsare used instead of character jumps. This can cause the jumps to be inthe middle of a character. In some cases this helps to decide that thereis no match. In some cases, when the jump is in the middle of acharacter, the system goes to the beginning of the character andproceeds with the system.

Initially, the minimum byte length of all the patterns is taken and thesystem jumps by the minimum pattern in the text. From that location,using the last three bytes, the hash value is calculated.

Referring now to FIG. 9B, an embodiment of the adapted or modified WuManber search technique is depicted. In brief overview, the method 900includes a pointer 990 set to the beginning of the identified text (atstep 902). At step 904, the pointer is moved to the pivot block 984 bytaking the minimum byte length and moving the pointer to (l_(min)−B). Atstep 906, the has value is calculated using the pre-determined number ofbytes in the pivot block and the jump value 986 is determined from thehash. At step 908, a determination is made as to whether the jump valueis equal to zero. If no, the jump value is set to 1 at step 912. If yes,then at step 910, identified patterns are check to see if any patternmatches are found. Then, at step 912, the jump value is set to 1. Atstep 914, a determination is made to see if the end of the text has beenreached. If no, then, the method returns to step 906 and continues untilthe end of the text is reached. If the end of the text has been reached,then at step 916, the search is terminated.

At step 902, a pointer 990 is set to the beginning of the text. Thepointer may be a pointer to an address or location within a block oftext, such as a pointer to a memory address. In some embodiments, thepointer is set to the beginning of the entire text. In otherembodiments, the pointer is set to the beginning of the portion of thetext identified by the user. In some embodiments, the pointer is set tothe beginning of the text, where the text has been divided into multipleportions.

At step 904, the pointer 990 is moved to the pivot block 984 by takingthe minimum byte length among all the patterns (l_(min)) and moving thepointer to the position found by (l_(min)−B). In some embodiments, B ispre-determined to be 3 bytes. In other embodiments, B can be anypre-determined size. In still other embodiments, B can be of variablesize.

At step 906, the hash value is calculated for the pivot block. Theminimal valid UTF-8 string that contains the bytes of the pivot blockare found and convert the string into lower case. From the lower casestring, the exact byte positions of the pivot block are found and thehash value is calculated for each byte. The jump value is thendetermined from the hash.

At step 908, it is determined whether the jump value is equal to zero.If the jump value is equal to zero then at step 910, the HASH table isconsulted. The HASH table at zero contains a lit of patterns that havezero jumps. Each of the patterns is then checked to see if there are anymatches to the pivot block. This search may require scanning the text byappropriate length based on the pattern length. If the position in thetext is not to a character boundary, the pattern can be skipped evenbefore comparing any characters. If the position in the text is at acharacter boundary, a case insensitive UTF-8 string comparison isperformed to check if the pattern matches that part of the text. If itmatches, then a match to this string is declared. The system continuesto match other strings in the list of patterns until the list for thishash is exhausted.

At step 912, the jump value is set to 1. The search continues and thesystem jumps in the text by the jump value. If such a jump exceeds thetext boundary, at step 914 declare no more matches. Otherwise, updatethe pivot block by taking the size of B and updating the pivot block tothe last bytes at the pointer to the size of B, for example three bytesand return to step 906 to continue searching until the end of the textis reached.

Now referring to FIG. 9C, a method for using an adapted, configured ormodified Horspool multi-pattern searching for multi-variable widthencoded data, such as UTF-8, is depicted. In brief overview, the method950 sets a pointer to the beginning of the text at step 952. At step954, the pointer is moved in the text to its pivot element based on thepattern length and the last character length. At step 956, the convertedlower case Unicode value of the pivot element is compared to thecorresponding value of the last character of the pattern. At step 958,it is determined whether there is a match. If yes, then at step 960, thematch position is declared. If no, then at step 962, the system, such asvia the search engine, jumps within the text by the jump value of thecurrent pivot element. At step 964, a determination is made as towhether the end of the text has been reached. If yes, then at step 968,the search terminates. If no, then return to step 956 and continue thesearch until the end of the text is reached and the search isterminated.

The multi-pattern search of 950 performs preprocessing of the pattern,as a means of determining how far to skip ahead in the search text if aninitial match attempt fails. The results of the preprocessing are savedin a vector that is used during the search process. The jump value of acharacter is its position from the end (without considering the lastbyte). If a byte is repeated in pattern, the minimum position is taken.Compare the last byte of the pattern with corresponding position in thetext. The jump is based on this text character, which is known as thepivot character.

For each UTF-8 character in the pattern, a corresponding Unicode valueis calculated. If character is upper case, then the corresponding lowercase Unicode value is calculated. In either case a hash is applied onthe Unicode value. Four hash tables 988 are maintained, one for eachsize as UTF-8 character can be at most 4 bytes (based on the statisticalanalysis, space restrictions and hash collisions, this can either bedecreased or increased). If there is a hash collision, the skip valueshould be minimum of two. That is because, in the absence of any hashcollisions, the jump value of a character ensures that after the jump,the pivot character of the text is aligned with the same character inthe pattern. Without such alignment, the system could not identify anymatch. In case of collision, by taking the minimum of the existing andnew values, the jump many not align the pivot in the text with the samecharacter in pattern, but it ensures that no matches are missed. Takingminimum of two hash values can be easily achieved by processing thepattern from the back instead of from front.

In the skip tables, the jump value of a character is its position in thepattern from the back. But if the character position in the jump table986 is kept, then the system would have to jump by those characters inUTF-8 text, and the system will be reduced to a character by charactermatching, which is far less efficient. Thus, the position of thecharacter in the pattern is not kept. Rather, in some embodiments, acorresponding byte length is used. That way, while using these values tojump in the text, the system can do a direct jump instead of countingthe characters.

The last character of the pattern is compared to the text. And if thereis a match, then the entire pattern is compared. To compare twocharacters case insensitively, the system needs to calculate theircorresponding lower (or upper) case Unicode values. Since the pattern isknown beforehand, in the pre-processing step, the system calculates thelowercase Unicode value of all the characters of the pattern and storesit. The byte length and the length of the last character of the patternare also stored.

The method requires jumping in the text. To retain the sub-linearrunning time complexity for date encoded by UTF-8, byte jumps are usedinstead of character jumps. This can cause the jumps to be in the middleof a character. In some cases this helps to decide that there is nomatch. In some cases, when in the middle of a character, the systemproceeds to the beginning of the character and proceeds with thealgorithm.

To determine the pivot element, the last character of the pattern andthe corresponding character in text to do a case-insensitive comparison.If the pattern has 5 characters, the system needs to go to the fifthcharacter in the text and compare it with fifth character of thepattern. But going to fifth character in text is linear time. So,instead the byte length of the pattern is used. Say if the lastcharacter length in pattern is 4, and if pattern is 20 bytes long, thenthe last character starts from 17th byte. In the text also, the systemgoes to the 17th byte directly and see if it is are aligned to acharacter boundary. The system goes to the nearest aligned charactertowards the beginning of the text. In either case the lowercase Unicodevalue of the character is found in the text (this value is the pivotelement). In case of a mismatch, the system finds the jump value of thisfrom jump tables 986 and jump in the text such that the comparison pointof the text is moved to the right and compare it with that of thepattern.

At step 952, a pointer is set to the beginning of the text. In someembodiments, the pointer is set to the beginning of the entire text. Inother embodiments, the pointer is set to the beginning of the portion ofthe text identified by the user. In some embodiments, the pointer is setto the beginning of the text, where the text has been divided intomultiple portions.

At step 954, based on the pattern length and last character length, thepointer is moved or jumped in the text to its pivot element. In theinitialization, if any such jump goes to the middle of a character, goto the next character. But in the subsequent steps, in case of any suchmisalignments, go to the beginning of the character.

At step 956, the lower case Unicode value of the pivot element iscompared against the corresponding value of the last character of thepattern. If the characters compared are same then compare the beginningof the pattern, and jump to the corresponding byte location of the textto compare the pattern against that part of the text. If the jump intext might be to the middle of a character, which clearly signifies nomatch. But if the jump is to a character boundary, then do a caseinsensitive comparison of the two strings.

At step 958, a determination is made as to whether there is a match. Ifyes, then at step 960, the match position is noted. In some embodiments,the match position is added to a hash table. In some embodiments, thematch position is transmitted to another module. In some embodiments,the match position is stored on the intermediary. If there is amismatch, then at step 962, the pointer is moved or jumped by the jumpvalue of the current pivot element.

At step 964, a determination is made as to whether the end of the texthas been reached. If yes, then at step 968, the search is terminated. Ifno, then return to step 956 and continue the search until the end of thetext is reached and the search is terminated.

It should be understood that the systems described above may providemultiple ones of any or each of those components and these componentsmay be provided on either a standalone machine or, in some embodiments,on multiple machines in a distributed system. In addition, the systemsand methods described above may be provided as one or morecomputer-readable programs or executable instructions embodied on or inone or more articles of manufacture. The article of manufacture may be afloppy disk, a hard disk, a CD-ROM, a flash memory card, a PROM, a RAM,a ROM, or a magnetic tape. In general, the computer-readable programsmay be implemented in any programming language, such as LISP, PERL, C,C++, C#, PROLOG, or in any byte code language such as JAVA. The softwareprograms or executable instructions may be stored on or in one or morearticles of manufacture as object code.

While the invention has been particularly shown and described withreference to specific embodiments, it should be understood by thoseskilled in the art that various changes in form and detail may be madetherein without departing from the spirit and scope of the disclosure.

What is claimed:
 1. A method for case insensitive searching of avariable width encoded pattern in a block of text, the methodcomprising: (a) determining, by a device, for each character in apattern for which to search for a match within a block of text, acorresponding lower case Unicode value, the pattern comprisingvariable-width encoded characters; (b) establishing, by the device, anindex table of jump values for the pattern, the index table comprising ahash to each corresponding lower case Unicode value that identifies anumber of byte lengths for the corresponding character; (c) jumping, bythe device responsive to the index table of jump values, a pointer tothe block of text to a pivot element in the block of text based on abyte length of the pattern and the byte length of a last character ofthe pattern; and (d) comparing, by the device, a lower case Unicodevalue of the pivot element to the corresponding lower case Unicode valueof the character of the last character of the pattern.
 2. The method ofclaim 1, wherein step (a) further comprises determining, by the device,that a character in the pattern is upper case and calculating a lowercase Unicode value.
 3. The method of claim 1, wherein the patterncomprises variable-width encoded characters that are UTF-8 encoded. 4.The method of claim 1, wherein step (b) further comprises establishing,by the device, index tables for each of size of variable-width encodedcharacters.
 5. The method of claim 1, wherein step (c) further comprisessetting, by the device, the pointer at a beginning of the block of text.6. The method of claim 1 wherein step (c) further comprises determining,by the device, that the pointer has jumped to a middle of a character inthe block of text.
 7. The method of claim 6, further comprising moving,by the device responsive to the determination that the pointer hasjumped to the middle of the character in the block of text, the pointerto beginning of the character.
 8. The method of claim 1, wherein step(d) further comprises determining, by the device, that the jump to thepivot element is a jump to a character boundary and responsive todetermining that the jump is to the character boundary, the deviceperforms the comparing.
 9. The method of claim 1, further comprisingdetermining, by the device, that the lower case Unicode value of thepivot element matches the corresponding lower case Unicode value of thecharacter of the last character of the pattern.
 10. The method of claim9, further comprising jumping, by the device, the pointer to the bytelocation in the block of text that corresponds to the beginning of thepattern and comparing the pattern against a corresponding portion of theblock of text identified by the pointer.
 11. A method for simultaneouslyperforming case insensitive searches of variable width encoded patternsin a block of text, the method comprising: (a) converting, by a device,each of the patterns to be searched within a block of text to acorresponding lower case pattern, each pattern comprising variable-widthencoded characters; (b) establishing, by the device for each of thepatterns, a shift table comprising a hash of a predetermined number ofbytes of the corresponding lower case pattern and a jump value; (c)jumping, by the device responsive to the shift table, a pointer to apivot block in the block of text; (d) identifying, by the device, anencoded string within the pivot block that comprises bytes from thepredetermined number of bytes of the pivot block; (e) computing, by thedevice, a hash of the bytes of the lower case of the encoded stringcorresponding to the predetermined number of bytes; and (f) obtaining,by the device using the hash of the bytes, the jump value from the shifttable.
 12. The method of claim 1, wherein the pattern comprisesvariable-width encoded characters that are UTF-8 encoded.
 13. The methodof claim 11, wherein step (b) further comprises maintaining, by thedevice, a list of patterns that have zero jumps at each hash.
 14. Themethod of claim 11, wherein step (c) further comprises initially jumpingby the device, the pointer to an initial pivot block based on a minimumbyte length across each of the patterns.
 15. The method of claim 11,wherein step (d) further comprises identifying, by the device, a minimalvalid encoded string comprising bytes from the predetermined number ofbytes of the pivot block.
 16. The method of claim 11, wherein step (f)further comprises identifying, by the device, that the jump value iszero.
 17. The method of claim 16, further comprising determining, by thedevice, whether any patterns associated with the jump value of zeromatch corresponding text in the block of text.
 18. The method of claim16, further comprising moving, by the device for each pattern, thepointer to the block of text back a number of byte lengths of thepattern.
 19. The method of claim 18, further comprising determining, bythe device, that the pattern does not match a corresponding portion oftext identified by the pointer responsive to identifying that thepointer is not a character boundary.
 20. The method of claim 18, furthercomprising comparing, by the device, the pattern to the text of theblock of text identified by the pointer responsive to identifying thatthe pointer is at a character boundary.